| 1. |
- Barakat, M. M. E., et al.
(författare)
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Superconducting gap and critical behavior in the Iron-Pnictides
- 2023
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Ingår i: RESULTS IN PHYSICS. - : ELSEVIER. - 2211-3797. ; 52
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Tidskriftsartikel (refereegranskat)abstract
- In the phase diagram of iron pnictides, superconductivity arises at the border of antiferromagnetism, which raises the question of the role of symmetry of the gap and quantum criticality. Although more than 15-years of extensive research, the microscopic origin of the pairing symmetry inside the superconducting (SC) dome and its link to quantum criticality still remains elusive. Here, we report two new findings on BaFe2_xNixAs2: (1) A sharp peak in the x-dependence of the lower and upper critical fields, the SC critical current density Jc, the size of the jump in the specific heat Delta Cel/T and the Sommerfeld coefficient (gamma) at the optimum composition x = 0.10, where the SC transition temperature Tc reaches a maximum. Our obtained reliable values as a function of doping of the normal-state Sommerfeld coefficient increase with doping, illustrating the strong competition between magnetism and superconductivity and attributed to closing of spin density wave gap with Ni doping. (2) We show that doping induced a sudden change of the gap structure from nodeless to nodal. Our results imply that the superconductivity in BaFe2_xNixAs2 is closely linked to the quantum criticality and is characterized by a complex order parameter.
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| 2. |
- Kamel, M., et al.
(författare)
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Optical, magnetic, thermodynamic, and dielectric studies of the disordered rock salt Li1.3Nb0.3Fe0.4O2 cathode for Li-ion batteries
- 2022
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 131:15
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Tidskriftsartikel (refereegranskat)abstract
- While most studies in disordered rock salt cathode materials focus on synthesis and electrochemical investigation, detailed investigations on their optical and thermodynamic properties are a matter of interest. Here, we report on complementary measurements of transient absorption spectroscopy, thermodynamic, and dielectric properties for Li1.3Nb0.3Fe0.4O2 (LNFO) disordered rock salt Li-excess. The structure was studied using powder x-ray diffraction and scanning electron microscopy, which showed the fine crystallization of LNFO. The ultra-fast laser spectroscopy is used to study the dynamics of charge carriers and electron-phonon coupling in the system. Our thermodynamic measurements have revealed a magnetically ordered phase with small spontaneous magnetization. The dielectric properties of LNFO illustrate high permittivity with losses at low frequencies. Furthermore, the behavior of the dielectric modulus and AC conductivity vs temperature and frequency were discussed.& nbsp;Published under an exclusive license by AIP Publishing.
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| 3. |
- Ghosh, Anirudha, et al.
(författare)
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Exotic magnetic and electronic properties of layered CrI3 single crystals under high pressure
- 2022
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 105:8
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Tidskriftsartikel (refereegranskat)abstract
- Through advanced experimental techniques on CrI3 single crystals, we derive a pressure-temperature phase diagram. We find that T-c increases to similar to 66 K with pressure up to similar to 3 GPa followed by a decrease to similar to 10 K at 21.2 GPa. The experimental results are reproduced by theoretical calculations based on density functional theory where electron-electron interactions are treated by a static on-site Hubbard U on Cr 3d orbitals. The origin of the pressure-induced reduction of the ordering temperature is associated with a decrease in the calculated bond angle, from 95 degrees at ambient pressure to similar to 85 degrees at 25 GPa. Above 22 GPa, experiment and theory jointly point to the idea that the ferromagnetically ordered state is destroyed, giving rise first to a complex, unknown magnetic configuration, and at sufficiently high pressures a pure antiferromagnetic configuration. This sequence of transitions in the magnetism is accompanied by a well-detected pressure-induced semiconductor-to-metal phase transition that is revealed by both high-pressure resistivity measurements and ab initio theory.
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| 4. |
- Fytory, Mostafa, et al.
(författare)
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Core-Shell Nanostructured Drug Delivery Platform Based on Biocompatible Metal-Organic Framework-Ligated Polyethyleneimine for Targeted Hepatocellular Carcinoma Therapy
- 2023
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Ingår i: ACS Omega. - : AMER CHEMICAL SOC. - 2470-1343. ; 8:23, s. 20779-20791
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Tidskriftsartikel (refereegranskat)abstract
- Multifunctional nanosized metal-organic frameworks(NMOFs)have advanced rapidly over the past decade to develop drug deliverysystems (DDSs). These material systems still lack precise and selectivecellular targeting, as well as the fast release of the quantity ofdrugs that are simply adsorbed within and on the external surfaceof nanocarriers, which hinders their application in the drug delivery.Herein, we designed a biocompatible Zr-based NMOF with an engineeredcore and the hepatic tumor-targeting ligand, glycyrrhetinic acid graftedto polyethyleneimine (PEI) as the shell. The improved core-shellserves as a superior nanoplatform for efficient controlled and activedelivery of the anticancer drug doxorubicin (DOX) against hepaticcancer cells (HepG2 cells). In addition to their high loading capacityof 23%, the developed nanostructure DOX@NMOF-PEI-GA showed an acidicpH-stimulated response and extended the drug release time to 9 daysas well as enhanced the selectivity toward the tumor cells. Interestingly,the DOX-free nanostructures showed a minimal toxic effect on bothnormal human skin fibroblast (HSF) and hepatic cancer cell line (HepG2),but the DOX-loaded nanostructures exhibited a superior killing effecttoward the hepatic tumor, thus opening the way for the active drugdelivery and achieving efficient cancer therapy applications.
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| 5. |
- Fytory, Mostafa, et al.
(författare)
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Dual-ligated metal organic framework as novel multifunctional nanovehicle for targeted drug delivery for hepatic cancer treatment
- 2021
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- In the last decade, nanosized metal organic frameworks (NMOFs) have gained an increasing applicability as multifunctional nanocarriers for drug delivery in cancer therapy. However, only a limited number of platforms have been reported that can serve as an effective targeted drug delivery system (DDSs). Herein, we report rational design and construction of doxorubicin (DOX)-loaded nanoscale Zr (IV)-based NMOF (NH2-UiO-66) decorated with active tumor targeting moieties; folic acid (FA), lactobionic acid (LA), glycyrrhetinic acid (GA), and dual ligands of LA and GA, as efficient multifunctional DDSs for hepatocellular carcinoma (HCC) therapy. The success of modification was exhaustively validated by various structural, thermal and microscopic techniques. Biocompatibility studies indicated the safety of pristine NH2-UiO-66 against HSF cells whereas DOX-loaded dual-ligated NMOF was found to possess superior cytotoxicity against HepG2 cells which was further confirmed by flow cytometry. Moreover, fluorescence microscopy was used for monitoring cellular uptake in comparison to the non-ligated and mono-ligated NMOF. Additionally, the newly developed dual-ligated NMOF depicted a pH-responsiveness towards the DOX release. These findings open new avenues in designing various NMOF-based DDSs that actively target hepatic cancer to achieve precise therapy.
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| 6. |
- Ghosh, Anirudha, et al.
(författare)
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Magnetic circular dichroism in the dd excitation in the van der Waals magnet CrI3 probed by resonant inelastic x-ray scattering
- 2023
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 107:11
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Tidskriftsartikel (refereegranskat)abstract
- We report on a combined experimental and theoretical study on CrI3 single crystals by employing the polarization dependence of resonant inelastic x-ray scattering (RIXS). Our investigations reveal multiple Cr 3d orbital splitting (dd excitations) as well as magnetic dichroism (MD) in the RIXS spectra. The dd excitation energies are similar on the two sides of the ferromagnetic transition temperature, T-C similar to 61 K, although MD in RIXS is predominant at 0.4 T magnetic field below TC. This demonstrates that the ferromagnetic superexchange interaction that is responsible for the interatomic exchange field is vanishingly small compared with the local exchange field that comes from exchange and correlation interaction among the interacting Cr 3d orbitals. The recorded RIXS spectra reported here reveal clearly resolved Cr 3d intraorbital dd excitations that represent transitions between electronic levels that are heavily influenced by dynamic correlations and multiconfiguration effects. Our calculations taking into account the Cr 3d hybridization with the ligand valence states and the full multiplet structure due to intra-atomic and crystal field interactions in Oh and D3d symmetry clearly reproduced the dichroic trend in experimental RIXS spectra.
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| 7. |
- Arneth, J., et al.
(författare)
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Uniaxial pressure effects in the two-dimensional van der Waals ferromagnet CrI3
- 2022
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 105:6
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Tidskriftsartikel (refereegranskat)abstract
- Magnetoelastic coupling and uniaxial pressure dependencies of the ferromagnetic ordering temperature in the quasi-two-dimensional layered van der Waals material CrI3 are experimentally studied and quantified by high-resolution dilatometry. Clear anomalies in the thermal expansion coefficients at T-C imply positive (negative) pressure dependencies partial derivative T-C/partial derivative p(i) for pressure applied along (perpendicular to) the c axis. The experimental results are backed up by numerical studies showing that the dominant, intralayer magnetic coupling increases upon compression along the c direction and decreases with negative in-plane strain. In contrast, interlayer exchange is shown to initially increase and subsequently decrease upon the application of both out-of-plane and in-plane compression.
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| 8. |
- Danilovich, I. L., et al.
(författare)
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Co(NO3)(2) as an inverted umbrella-type chiral noncoplanar ferrimagnet
- 2020
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Ingår i: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 102:9
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Tidskriftsartikel (refereegranskat)abstract
- The low-dimensional magnetic systems tend to reveal exotic spin-liquid ground states or form peculiar types of long-range order. Among systems of vivid interest are those characterized by the triangular motif in two dimensions. The realization of either ordered or disordered ground state in triangular, honeycomb, or kagome lattices is dictated by the competition of exchange interactions, also being sensitive to anisotropy and the spin value of magnetic ions. While the low-spin Heisenberg systems may arrive to a spin-liquid long-range entangled quantum state with emergent gauge structures, the high-spin Ising systems may establish the rigid noncollinear structures. Here, we present the case of chiral noncoplanar inverted umbrella-type ferrimagnet formed in cobalt nitrate Co(NO3)(2) below T-C = 3 K with the comparable spin and orbital contributions to the total magnetic moment.
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| 9. |
- Elsayed, Mohamed Hammad, et al.
(författare)
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Hydrophobic and Hydrophilic Conjugated Polymer Dots as Binary Photocatalysts for Enhanced Visible-Light-Driven Hydrogen Evolution through Forster Resonance Energy Transfer
- 2021
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 13:47, s. 56554-56565
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Tidskriftsartikel (refereegranskat)abstract
- Organic semiconducting polymers exhibited promising photocatalytic behavior for hydrogen (H-2) evolution, especially when prepared in the form of polymer dots (Pdots). However, the Pdot structures were formed using common nonconjugated amphiphilic polymers, which have a negative effect on charge transfer between photocatalysts and reactants and are unable to participate in the photocatalytic reaction. This study presents a new strategy for constructing binary Pdot photocatalysts by replacing the nonconjugated amphiphilic polymer typically employed in the preparation of polymer nanoparticles (Pdots) with a low-molecular-weight conjugated polyelectrolyte. The as-prepared polyelectrolyte/hydrophobic polymer-based binary Pdots truly enhance the electron transfer between the Pt cocatalyst and the polymer photocatalyst with good water dispersibility. Moreover, unlike the nonconjugated amphiphilic polymer, the photophysics and mechanism of this photocatalytic system through time-correlated single-photon counting (TCSPC) and transient absorption (TA) measurements confirmed the Forster resonance energy transfer (FRET) between the polyelectrolyte as a donor and the hydrophobic polymer as an acceptor. As a result, the designated binary Pdot photocatalysts significantly enhanced the hydrogen evolution rate (HER) of 43 900 mu mol g(-1) h(-1) (63.5 mu mol h(-1), at 420 nm) for PTTPA/PFTBTA Pdots under visible-light irradiation.
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| 10. |
- Hoffmann, M., et al.
(författare)
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Magnetic phase diagram, magnetoelastic coupling, and Grüneisen scaling in CoTiO3
- 2021
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 104:1
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Tidskriftsartikel (refereegranskat)abstract
- High-quality single crystals of CoTiO3 are grown and used to elucidate in detail structural and magnetostructural effects by means of high-resolution capacitance dilatometry studies in fields up to 15 T which are complemented by specific heat and magnetization measurements. In addition, we refine the single-crystal structure of the ilmenite (R (3) over bar) phase. At the antiferromagnetic ordering temperature T-N pronounced lambda-shaped anomaly in the thermal expansion coefficients signals shrinking of both the c and b axes, indicating strong magnetoelastic coupling with uniaxial pressure along c yielding six times larger effect on T-N than pressure applied in-plane. The hydrostatic pressure dependency derived by means of Gruneisen analysis amounts to partial derivative T-N/partial derivative p approximate to 2.7(4) K/GPa. The high-field magnetization studies in static and pulsed magnetic fields up to 60 T along with high-field thermal expansion measurements facilitate in constructing the complete anisotropic magnetic phase diagram of CoTiO3. While the results confirm the presence of significant magnetodielectric coupling, our data show that magnetism drives the observed structural, dielectric, and magnetic changes both in the short-range ordered regime well above T-N as well as in the long-range magnetically ordered phase.
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