| 1. |
- Abbondanza, Giuseppe, et al.
(författare)
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Anisotropic strain variations during the confined growth of Au nanowires
- 2023
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 122:12
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Tidskriftsartikel (refereegranskat)abstract
- The electrochemical growth of Au nanowires in a template of nanoporous anodic aluminum oxide was investigated in situ by means of grazing-incidence transmission small- and wide-angle x-ray scattering (GTSAXS and GTWAXS), x-ray fluorescence (XRF), and two-dimensional surface optical reflectance. The XRF and the overall intensity of the GTWAXS patterns as a function of time were used to monitor the progress of the electrodeposition. Furthermore, we extracted powder diffraction patterns in the direction of growth and in the direction of confinement to follow the evolution of the direction-dependent strain. Quite rapidly after the beginning of the electrodeposition, the strain became tensile in the vertical direction and compressive in the horizontal direction, which showed that the lattice deformation of the nanostructures can be artificially varied by an appropriate choice of the deposition time. By alternating sequences of electrodeposition with sequences of rest, we observed fluctuations of the lattice parameter in the direction of growth, attributed to stress caused by electromigration. Furthermore, the porous domain size calculated from the GTSAXS patterns was used to monitor how homogeneously the pores were filled.
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| 2. |
- Albertsson, Dagur Ingi, et al.
(författare)
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Ultrafast Ising Machines using spin torque nano-oscillators
- 2021
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 118:11
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Tidskriftsartikel (refereegranskat)abstract
- Combinatorial optimization problems are known for being particularly hard to solve on traditional von Neumann architectures. This has led to the development of Ising Machines (IMs) based on quantum annealers and optical and electronic oscillators, demonstrating speed-ups compared to central processing unit (CPU) and graphics processing unit (GPU) algorithms. Spin torque nano-oscillators (STNOs) have shown GHz operating frequency, nanoscale size, and nanosecond turn-on time, which would allow their use in ultrafast oscillator-based IMs. Here, we show using numerical simulations based on STNO auto-oscillator theory that STNOs exhibit fundamental characteristics needed to realize IMs, including in-phase/out-of-phase synchronization and second harmonic injection locking phase binarization. Furthermore, we demonstrate numerically that large STNO network IMs can solve Max-Cut problems on nanosecond timescales.
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| 3. |
- Andersen, André, et al.
(författare)
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As-deposited ferroelectric HZO on a III–V semiconductor
- 2022
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 121:1, s. 012901-012901
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Tidskriftsartikel (refereegranskat)abstract
- By electrical characterization of thin films deposited by atomic layer deposition, HfxZr1−xO2 (HZO) is shown to be ferroelectric as-deposited, i.e., without any annealing step, using a thermal budget of 300 °C. By fabricating laminated HZO films rather than the traditional solid-solution HZO, a remanent polarization of Pr = 11 μC/cm2 and endurance exceeding 106 are obtained. Films grown on thermally reactive InAs semiconductor substrates showed capacitance–voltage modulation and hysteresis, which varied depending on interfacial oxide construction. Additionally, a trade-off between higher polarization and lower gate leakage was found when comparing different laminate structures and deposition temperatures. Scaling the thickness of the laminated oxides revealed that films remain ferroelectric at 6.5 nm with an increased breakdown field for thinner devices.
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| 4. |
- Andrearczyk, Tomasz, et al.
(författare)
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Current-induced magnetization reversal in (Ga,Mn)(Bi,As) epitaxial layer with perpendicular magnetic anisotropy
- 2022
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 121:24
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Tidskriftsartikel (refereegranskat)abstract
- Pulsed current-induced magnetization reversal is investigated in the layer of (Ga,Mn)(Bi,As) dilute ferromagnetic semiconductor (DFS) epitaxially grown under tensile misfit strain causing perpendicular magnetic anisotropy in the layer. The magnetization reversal, recorded through measurements of the anomalous Hall effect, appearing under assistance of a static magnetic field parallel to the current, is interpreted in terms of the spin-orbit torque mechanism. Our results demonstrate that an addition of a small fraction of heavy Bi atoms, substituting As atoms in the prototype DFS (Ga,Mn)As and increasing the strength of spin-orbit coupling in the DFS valence band, significantly enhances the efficiency of current-induced magnetization reversal thus reducing considerably the threshold current density necessary for the reversal. Our findings are of technological importance for applications to spin-orbit torque-driven nonvolatile memory and logic elements. Published under an exclusive license by AIP Publishing.
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| 5. |
- Andres, Beatrice, et al.
(författare)
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Strong momentum-dependent electron-magnon renormalization of a surface resonance on iron
- 2022
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 120:20
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Tidskriftsartikel (refereegranskat)abstract
- The coupling of electrons to spin excitations and the generation of magnons is essential for spin mixing in the ultrafast magnetization dynamics of 3d ferromagnets. Although magnon energies are generally much larger than phonon energies, until now their electronic band renormalization effect in 3d ferromagnets suggests a significantly weaker quasiparticle interaction. Using spin- and angle-resolved photoemission, we show an extraordinarily strong renormalization leading to two-branch splitting of an iron surface resonance at ~& nbsp;200 meV. Its strong magnetic linear dichroism unveils the magnetic nature and momentum dependence of the energy renormalization. By determining the frequency- and momentum-dependent self-energy due to generic electron-boson interaction to compute the resultant electron spectral function, we suggest that the surface-state splitting can be described by strong coupling to an optical spin wave in an iron thin film.& nbsp;& nbsp;Published under an exclusive license by AIP Publishing.
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| 6. |
- Auroux, Etienne, et al.
(författare)
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Ion transfer into solution-processed electrodes can significantly shift the p-n junction and emission efficiency of light-emitting electrochemical cells
- 2022
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 121:23
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Tidskriftsartikel (refereegranskat)abstract
- A light-emitting electrochemical cell (LEC) comprises mobile ions in its active material, which enable for in situ formation of a p-n junction by electrochemical doping. The position of this emissive p-n junction in the interelectrode gap is important, because it determines whether the emission is affected by constructive or destructive interference. An appealing LEC feature is that the entire device can be fabricated by low-cost solution-based printing and coating. Here, we show, somewhat unexpectedly, that the replacement of conventional vacuum-deposited indium-tin-oxide (ITO) for the positive anode with solution-processed poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) can result in an increase in the peak light-emission output by 75%. We demonstrate that this emission increase is due to that the p-n junction shifts from a position of destructive interference in the center of the interelectrode gap with ITO to a position of constructive interference closer to the anode with PEDOT:PSS. We rationalize the anodic p-n junction shift by significant anion transfer into the soft and porous PEDOT:PSS electrode during LEC operation, which is prohibited for the ITO electrode because of its compact and hard nature. Our study, thus, contributes with important design criteria for the attainment of efficient light emission from solution-processed LEC devices.
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| 7. |
- Awad, Ahmad, et al.
(författare)
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Femtosecond laser comb driven perpendicular standing spin waves
- 2022
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 120:1
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Tidskriftsartikel (refereegranskat)abstract
- We study femtosecond laser comb driven sustained and coherent spin wave (SW) generation in Permalloy films over a thickness range of d = 40-100 nm. A simple rapid demagnetization model describes the dependence of the observed SW intensity on laser power for all film thicknesses. In the thicker films, we observe laser comb excited perpendicular standing spin waves up to the third order and to 18 multiples of the 1 GHz laser repetition rate. Our results demonstrate the versatility of femtosecond combs as contact-less SW point sources over a wide range of film thickness and type of SW modes.
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| 8. |
- Awad, Ahmad, et al.
(författare)
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Width dependent auto-oscillating properties of constriction based spin Hall nano-oscillators
- 2020
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 116:23
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Tidskriftsartikel (refereegranskat)abstract
- We study the current tunable microwave signal properties of nano-constriction-based spin Hall nano-oscillators in oblique magnetic fields as a function of the nano-constriction width, w = 50 - 140 nm. The threshold current is found to scale linearly with w, defining a constant threshold current density of Jth = 1.7 x 10(8) A/cm(2). While the current dependence of the microwave frequency shows the same generic non-monotonic behavior for all w >= 80 nm, the quality of the generated microwave signal improves strongly with w, as the total power increases and the linewidth decreases linearly with w. As a consequence, the peak power for a 140 nm nano-constriction is about an order of magnitude higher than that for an 80 nm nano-constriction. The smallest nano-constriction, w = 50 nm, exhibits a different behavior with a higher power and a worse linewidth, indicating a crossover into a qualitatively different narrow-constriction regime.
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| 9. |
- Barthelmi, K., et al.
(författare)
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Atomistic defects as single-photon emitters in atomically thin MoS2
- 2020
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 117:7
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Tidskriftsartikel (refereegranskat)abstract
- Precisely positioned and scalable single-photon emitters (SPEs) are highly desirable for applications in quantum technology. This Perspective discusses single-photon-emitting atomistic defects in monolayers of MoS2 that can be generated by focused He-ion irradiation with few nanometers positioning accuracy. We present the optical properties of the emitters and the possibilities to implement them into photonic and optoelectronic devices. We showcase the advantages of the presented emitters with respect to atomistic positioning, scalability, long (microsecond) lifetime, and a homogeneous emission energy within ensembles of the emitters. Moreover, we demonstrate that the emitters are stable in energy on a timescale exceeding several weeks and that temperature cycling narrows the ensembles' emission energy distribution.
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| 10. |
- Bergmann, Michael Alexander, 1989, et al.
(författare)
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Thin-film flip-chip UVB LEDs realized by electrochemical etching
- 2020
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 116:12, s. 121101-
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a thin-film flip-chip (TFFC) light-emitting diode (LED) emitting in the ultraviolet B (UVB) at 311 nm, where substrate removal has been achieved by electrochemical etching of a sacrificial Al0.37Ga0.63N layer. The electroluminescence spectrum of the TFFC LED corresponds well to the as-grown LED structure, showing no sign of degradation of structural and optical properties by electrochemical etching. This is achieved by a proper epitaxial design of the sacrificial layer and the etch stop layers in relation to the LED structure and the electrochemical etch conditions. Enabling a TFFC UV LED is an important step toward improving the light extraction efficiency that limits the power conversion efficiency in AlGaN-based LEDs.
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| 11. |
- Bhardwaj, Vishal, et al.
(författare)
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Observation of surface dominated topological transport in strained semimetallic ErPdBi thin films
- 2020
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 117:13
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Tidskriftsartikel (refereegranskat)abstract
- In this Letter, we present experimental observation of surface-dominated transport properties in [110]-oriented strained (∼1.6%) ErPdBi thin films. The resistivity data show typical semi-metallic behavior in the temperature range of 3 K ≤ T ≤ 350 K with a transition from semiconductor- to metal-like behavior below 3 K. The metallic behavior at low temperature disappears entirely in the presence of an external magnetic field >1 T. The weak-antilocalization (WAL) effect is observed in magneto-conductance data in the low magnetic field region and follows the Hikami-Larkin-Nagaoka (HLN) model. HLN fitting estimated single coherent channel, i.e., α ∼-0.51 at 1.9 K, and the phase coherence length (Lφ) shows the Lφ ∼T-0.52 power law dependence on temperature in the range of 1.9 K-10 K, indicating the observation of 2D WAL. Shubnikov-de Haas (SdH) oscillations are observed in magneto-resistance data below 10 K and are fitted to standard Lifhsitz Kosevich theory. Fitting reveals the effective mass of charge carriers ∼0.15 me and a finite Berry phase of 0.86π± 0.16. The sheet carrier concentration and mobility of carriers estimated using SdH data are ns ∼1.35 × 1012 cm-2 and μs = 1210 cm2 V-1 s-1, respectively, and match well with the data measured using the Hall measurement at 1.9 K to be n ∼1.22 × 1012 cm-2, μ = 1035 cm2 V-1 s-1. These findings indicate the non-trivial nature and surface-dominated transport properties of strained (110) ErPdBi thin films at low temperatures.
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| 12. |
- Borynskyi, V. Yu, et al.
(författare)
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Higher-order ferromagnetic resonances in periodic arrays of synthetic-antiferromagnet nanodisks
- 2021
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 119:19
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Tidskriftsartikel (refereegranskat)abstract
- We investigate spin dynamics in nanodisk arrays of synthetic-antiferromagnets (SAF) made of Py/NiCu/Py trilayers, where the NiCu spacer undergoes a Curie transition at about 200 K. The observed ferromagnetic resonance spectra have three distinct resonance modes at room temperature, which are fully recreated in our micromagnetic simulations, showing also how the intra-SAF asymmetry can be used to create and control the higher-order resonances in the structure. Below the Curie temperature of the spacer, the system effectively transitions into a single-layer nanodisk array with only two resonance modes. Our results show how multilayering of nanoarrays can add tunable GHz functionality relevant for such rapidly developing fields as magnetic metamaterials, magnonic crystals, arrays of spin-torque oscillators, and neuromorphic junctions.
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| 13. |
- Cardinali, G., et al.
(författare)
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Low-Threshold AlGaN-based UVB VCSELs enabled by post-growth cavity detuning
- 2022
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 121:10
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Tidskriftsartikel (refereegranskat)abstract
- The performance of vertical-cavity surface-emitting lasers (VCSELs) is strongly dependent on the spectral detuning between the gain peak and the resonance wavelength. Here, we use angle-resolved photoluminescence spectroscopy to investigate the emission properties of AlGaN-based VCSELs emitting in the ultraviolet-B spectral range with different detuning between the photoluminescence peak of the quantum-wells and the resonance wavelength. Accurate setting of the cavity length, and thereby the resonance wavelength, is accomplished by using doping-selective electrochemical etching of AlGaN sacrificial layers for substrate removal combined with deposition of dielectric spacer layers. By matching the resonance wavelength to the quantum-wells photoluminescence peak, a threshold power density of 0.4 MW/cm2 was achieved, and this was possible only for smooth etched surfaces with a root mean square roughness below 2 nm. These results demonstrate the importance of accurate cavity length control and surface smoothness to achieve low-Threshold AlGaN-based ultraviolet VCSELs.
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| 14. |
- Chen, Hao, et al.
(författare)
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Tuning the dynamics in Fe3O4nanoparticles for hyperthermia optimization
- 2020
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Ingår i: Applied Physics Letters. - : American Institute of Physics Inc.. - 0003-6951 .- 1077-3118. ; 117:7
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Tidskriftsartikel (refereegranskat)abstract
- The AC magnetic susceptibility (ACS) of Fe3O4 nanoparticles was measured between 10 kHz and 4 MHz at different temperatures and in applied DC fields. In this frequency range, magnetostatic interactions impact magnetization dynamics even for dilute assemblies. The ACS spectrum of relaxation frequencies changes both with temperature and the addition of a small DC field. Because both the relaxation peak frequency and amplitude can be tuned with the DC field, these results could be applied to magnetic hyperthermia applications to optimize heat delivery.
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| 15. |
- Chen, Qiao, et al.
(författare)
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Anisotropic glide-symmetric substrate-integrated-holey metasurface for a compressed ultrawideband Luneburg lens
- 2021
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Ingår i: Applied Physics Letters. - : AMER INST PHYSICS. - 0003-6951 .- 1077-3118. ; 118:8
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Tidskriftsartikel (refereegranskat)abstract
- An anisotropic unit cell based on glide symmetry is proposed for tailoring a metasurface that engineers an optically transformed Luneburg lens. Thanks to the optical transformation, the size of the lens is reduced by 25%. The proposed lens is ultrawideband, and it covers multi-octave frequency bands. The required constitutive materials are achieved in an air gap bounded by top and bottom glide-symmetric metasurfaces; i.e., they are off-shifted by half the period. Each surface is implemented in standard printed-circuit-board technology, and its unit cell consists of a grounded substrate with an elliptical holey top cladding surrounded by metalized through-vias. This technology, known as substrate-integrated-holes (SIHs), mimics the operation of holes drilled in a parallel plate but provides the higher effective refractive index required for lens compression. The SIH is attractive for practical applications since most of the energy propagates in the air gap between the two surfaces and, therefore, it features low dielectric losses. Thanks to glide symmetry, the proposed metasurface demonstrates a further enhanced effective refractive index with lower dispersion over an ultra-wide bandwidth in comparison to its non-glide counterpart. A multimodal transfer-matrix approach is here employed to carry out the Bloch analysis of the proposed SIH. Published under license by AIP Publishing.
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| 16. |
- Chen, Xin, et al.
(författare)
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Giant spin-splitting and tunable spin-momentum locked transport in room temperature collinear antiferromagnetic semimetallic CrO monolayer
- 2023
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 123:2
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we present theoretical predictions of a two-dimensional collinear antiferromagnetic semimetal, CrO, which exhibits a giant spin-split band structure, spin-momentum locked transport properties, and a high Neel temperature. Specifically, CrO features two pairs of spin-polarized anisotropic Weyl points at the Fermi level. By manipulating the position of these Weyl points with strain, we demonstrate that four different antiferromagnetic spintronic states with zero net magnetic moments can be achieved, including semimetals with two spin-polarized transport channels, half-semimetals, semiconductors with two spin-polarized transport channels, and half-semiconductors. The strain-induced semiconducting state also preserves the ultra-high carrier mobility of Weyl points, and the bandgap can be easily tuned. These findings offer a good avenue in spintronics without net magnetic moment or strong spin-orbit coupling and could lead to the development of antiferromagnetic materials for spintronic applications.
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| 17. |
- Chen, Yan, et al.
(författare)
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Gate-tunable superconductivity in hybrid InSb-Pb nanowires
- 2023
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Ingår i: Applied Physics Letters. - 0003-6951 .- 1077-3118. ; 123:8
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Tidskriftsartikel (refereegranskat)abstract
- We present a report on hybrid InSb-Pb nanowires that combine high spin-orbit coupling with a high critical field and a large superconducting gap. Material characterization indicates the Pb layer of high crystal quality on the nanowire side facets. Hard induced superconducting gaps and gate-tunable supercurrent are observed in the hybrid nanowires. These results showcase the promising potential of this material combination for a diverse range of applications in hybrid quantum transport devices.
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| 18. |
- Chen, Yang, et al.
(författare)
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Semiconductor nanowire array for transparent photovoltaic applications
- 2021
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 118:19
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Tidskriftsartikel (refereegranskat)abstract
- The surface area of a building that could potentially be used for Building Integrated Photovoltaics would increase dramatically with the availability of transparent solar cells that could replace windows. The challenge is to capture energy from outside the visible region (UV or IR) while simultaneously allowing a high-quality observation of the outside world and transmitting sufficient light in the visible region to satisfactorily illuminate the interior of the building. In this paper, we show both computationally and experimentally that InP nanowire arrays can have good transparency in the visible region and high absorption in the near-infrared region. We show experimentally that we can achieve mean transparencies in the visible region of 65% and the radiative limit of more than 10% based on measured absorption and calculated emission. Our results demonstrate that nanowire arrays hold promise as a method to achieve transparent solar cells, which would fulfill the requirements to function as windows. In addition, we show that by optical design and by designing the geometry of nanowire arrays, solar cells can be achieved that absorb/transmit at wavelengths that are not decided by the bandgap of the material and that can be tailored to specific requirements such as colorful windows.
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| 19. |
- Chih-Wei, Chih-Wei, et al.
(författare)
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Direct epitaxial nanometer-thin InN of high structural quality on 4H-SiC by atomic layer deposition
- 2020
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Ingår i: Applied Physics Letters. - : AMER INST PHYSICS. - 0003-6951 .- 1077-3118. ; 117:9
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Tidskriftsartikel (refereegranskat)abstract
- Indium nitride (InN) is a highly promising material for high frequency electronics given its low bandgap and high electron mobility. The development of InN-based devices is hampered by the limitations in depositing very thin InN films of high quality. We demonstrate growth of high-structural-quality nanometer thin InN films on 4H-SiC by atomic layer deposition (ALD). High resolution x-ray diffraction and transmission electron microscopy show epitaxial growth and an atomically sharp interface between InN and 4H-SiC. The InN film is fully relaxed already after a few atomic layers and shows a very smooth morphology where the low surface roughness (0.14nm) is found to reproduce sub-nanometer surface features of the substrate. Raman measurements show an asymmetric broadening caused by grains in the InN film. Our results show the potential of ALD to prepare high-quality nanometer-thin InN films for subsequent formation of heterojunctions.
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| 20. |
- Chioar, Ioan-Augustin, et al.
(författare)
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Steering light with magnetic textures
- 2022
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 120:3
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Tidskriftsartikel (refereegranskat)abstract
- We study the steering of visible light using a combination of magneto-optical effects and the reconfigurability of magnetic domains in yttrium-iron garnet films. The spontaneously formed stripe domains are used as a field-controlled optical grating, allowing for active spatiotemporal control of light. We discuss the basic ideas behind the approach and provide a quantitative description of the field dependence of the obtained light patterns. Finally, we calculate and experimentally verify the efficiency of our magneto-optical grating.
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| 21. |
- Ciers, Joachim, 1991, et al.
(författare)
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Smooth GaN membranes by polarization-assisted electrochemical etching
- 2021
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 118:6
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Tidskriftsartikel (refereegranskat)abstract
- III-nitride membranes offer promising perspectives and improved device designs in photonics, electronics, and optomechanics. However, the removal of the growth substrate often leads to a rough membrane surface, which increases scattering losses in optical devices. In this work, we demonstrate membranes with etched surface roughness comparable to that of the as-grown epitaxial material, accomplished by the implementation of a properly designed built-in polarization field near the top of the sacrificial layer from an AlInN interlayer, which is polarization-mismatched to GaN. This leads to a steeper reduction in free carrier density during the electrochemical etching of the sacrificial layer, limiting the etching current and thus causing an abrupter etch stop. As a result, the root mean square roughness is reduced to 0.4nm over 5x5 mu m(2). These smooth membranes open attractive pathways for the fabrication of high-quality optical cavities and waveguides operating in the ultraviolet and visible spectral regions.
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| 22. |
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| 23. |
- de Graaf, Sebastian Erik, 1986, et al.
(författare)
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Scaling of self-stimulated spin echoes
- 2024
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Ingår i: Applied Physics Letters. - 0003-6951 .- 1077-3118. ; 124:2
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Tidskriftsartikel (refereegranskat)abstract
- Self-stimulated echoes have recently been reported in the high cooperativity and inhomogeneous coupling regime of spin ensembles with superconducting resonators. In this work, we study their relative amplitudes using echo-silencing made possible by a fast frequency tunable resonator. The highly anisotropic spin linewidth of Er3+ electron spins in the CaWO4 crystal also allows to study the dependence on spin-resonator ensemble cooperativity. It is demonstrated that self-stimulated echoes primarily result from a combination of two large control pulses and the echo preceding it.
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| 24. |
- Dong, Zhihua, et al.
(författare)
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Thermo-mechanical properties of Cr-Co-Ni alloys from longitudinal spin fluctuation theory
- 2021
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 119:8
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Tidskriftsartikel (refereegranskat)abstract
- Accounting for longitudinal spin fluctuations in the paramagnetic state, we calculate elastic constants and stacking fault energy as a function of temperature and chemical composition for Cr-Co-Ni alloys. The longitudinal spin fluctuations are demonstrated to be important for the quantitative description of the thermo-mechanical properties and the corresponding chemical and temperature dependences. Replacing Ni with Cr and Co is found to yield opposite influence on the mechanical properties at finite temperature. A high thermal stability in plasticity is predicted in the low Cr regime in Cr-Co-Ni alloys, while a good thermal stability in elasticity can be achieved in the high Cr and low Co regime. The present advance in thermo-chemical-magnetic-property enhances the understanding required for an intelligent design of multicomponent alloys toward high-technology applications. Published under an exclusive license by AIP Publishing.
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| 25. |
- Du, Wanyi, et al.
(författare)
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Photodoping of graphene/silicon van der Waals heterostructure observed by terahertz emission spectroscopy
- 2020
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 117:8
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Tidskriftsartikel (refereegranskat)abstract
- Photodoping as a nonvolatile and reversible method can be used to modify the carrier distribution at the heterojunction interface. Herein, we explore the 2D/3D van der Waals (vdW) graphene/silicon (G/Si) heterostructure in real time by terahertz (THz) emission spectroscopy. Photoinduced doping is introduced by a continuous wave laser, which leads to a screening effect to the built-in electric field at the interface. The resulting decrease in transient photocurrent reduces the THz emission amplitude from the G/Si heterostructure. The photoinduced doping effect suggests a 40% THz intrinsic modulation depth at external reverse bias. This work provides an effective way to actively control the THz emission process from the G/Si interface and paves the way for analyzing the interfacial process under photoinduced doping in vdW heterostructures.
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