| 11. |
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| 12. |
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| 13. |
- Martinez-Castro, Jose, et al.
(författare)
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Electric polarization switching in an atomically thin binary rock salt structure
- 2018
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Ingår i: Nature Nanotechnology. - : Springer Science and Business Media LLC. - 1748-3387 .- 1748-3395. ; 13:1, s. 19-23
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Tidskriftsartikel (refereegranskat)abstract
- Inducing and controlling electric dipoles is hindered in the ultrathin limit by the finite screening length of surface charges at metal-insulator junctions 1-3, although this effect can be circumvented by specially designed interfaces 4 . Heterostructures of insulating materials hold great promise, as confirmed by perovskite oxide superlattices with compositional substitution to artificially break the structural inversion symmetry 5-8 . Bringing this concept to the ultrathin limit would substantially broaden the range of materials and functionalities that could be exploited in novel nanoscale device designs. Here, we report that non-zero electric polarization can be induced and reversed in a hysteretic manner in bilayers made of ultrathin insulators whose electric polarization cannot be switched individually. In particular, we explore the interface between ionic rock salt alkali halides such as NaCl or KBr and polar insulating Cu2N terminating bulk copper. The strong compositional asymmetry between the polar Cu2N and the vacuum gap breaks inversion symmetry in the alkali halide layer, inducing out-of-plane dipoles that are stabilized in one orientation (self-poling). The dipole orientation can be reversed by a critical electric field, producing sharp switching of the tunnel current passing through the junction.
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| 14. |
- Plesa, Calin, et al.
(författare)
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Direct observation of DNA knots using a solid-state nanopore
- 2016
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Ingår i: Nature Nanotechnology. - : NATURE PUBLISHING GROUP. - 1748-3387 .- 1748-3395. ; 11:12, s. 1093-1097
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Tidskriftsartikel (refereegranskat)abstract
- Long DNA molecules can self-entangle into knots. Experimental techniques for observing such DNA knots (primarily gel electrophoresis) are limited to bulk methods and circular molecules below 10 kilobase pairs in length. Here, we show that solid-state nanopores can be used to directly observe individual knots in both linear and circular single DNA molecules of arbitrary length. The DNA knots are observed as short spikes in the nanopore current traces of the traversing DNA molecules and their detection is dependent on a sufficiently high measurement resolution, which can be achieved using high-concentration LiCI buffers. We study the percentage of molecules with knots for DNA molecules of up to 166 kilobase pairs in length and find that the knotting occurrence rises with the length of the DNA molecule, consistent with a constant knotting probability per unit length. Our experimental data compare favourably with previous simulation based predictions for long polymers. From the translocation time of the knot through the nanopore, we estimate that the majority of the DNA knots are tight, with remarkably small sizes below 100 nm. In the case of linear molecules, we also observe that knots are able to slide out on application of high driving forces (voltage).
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| 15. |
- Raja, A., et al.
(författare)
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Dielectric disorder in two-dimensional materials
- 2019
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Ingår i: Nature Nanotechnology. - : Springer Science and Business Media LLC. - 1748-3387 .- 1748-3395. ; 14:9, s. 832-837
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Tidskriftsartikel (refereegranskat)abstract
- Understanding and controlling disorder is key to nanotechnology and materials science. Traditionally, disorder is attributed to local fluctuations of inherent material properties such as chemical and structural composition, doping or strain. Here, we present a fundamentally new source of disorder in nanoscale systems that is based entirely on the local changes of the Coulomb interaction due to fluctuations of the external dielectric environment. Using two-dimensional semiconductors as prototypes, we experimentally monitor dielectric disorder by probing the statistics and correlations of the exciton resonances, and theoretically analyse the influence of external screening and phonon scattering. Even moderate fluctuations of the dielectric environment are shown to induce large variations of the bandgap and exciton binding energies up to the 100 meV range, often making it a dominant source of inhomogeneities. As a consequence, dielectric disorder has strong implications for both the optical and transport properties of nanoscale materials and their heterostructures.
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| 16. |
- Reiss, T., et al.
(författare)
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Graphene is on track to deliver on its promises
- 2019
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Ingår i: Nature Nanotechnology. - : Springer Science and Business Media LLC. - 1748-3387 .- 1748-3395. ; 14:10, s. 907-910
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 17. |
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| 18. |
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| 19. |
- Sluka, Volker, et al.
(författare)
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Emission and propagation of 1D and 2D spin waves with nanoscale wavelengths in anisotropic spin textures
- 2019
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Ingår i: Nature Nanotechnology. - : Springer Nature. - 1748-3387 .- 1748-3395. ; 14:4, s. 328-333
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Tidskriftsartikel (refereegranskat)abstract
- Spin waves offer intriguing perspectives for computing and signal processing, because their damping can be lower than the ohmic losses in conventional complementary metal-oxide-semiconductor (CMOS) circuits. Magnetic domain walls show considerable potential as magnonic waveguides for on-chip control of the spatial extent and propagation of spin waves. However, low-loss guidance of spin waves with nanoscale wavelengths and around angled tracks remains to be shown. Here, we demonstrate spin wave control using natural anisotropic features of magnetic order in an interlayer exchange-coupled ferromagnetic bilayer. We employ scanning transmission X-ray microscopy to image the generation of spin waves and their propagation across distances exceeding multiples of the wavelength. Spin waves propagate in extended planar geometries as well as along straight or curved one-dimensional domain walls. We observe wavelengths between 1 mu m and 150 nm, with excitation frequencies ranging from 250 MHz to 3 GHz. Our results show routes towards the practical implementation of magnonic waveguides in the form of domain walls in future spin wave logic and computational circuits.
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| 20. |
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