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Your search keyword '"Guo, G.Y."' showing total 105 results
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105 results on '"Guo, G.Y."'

14. Conductance fluctuations in disordered 2D topological insulator wires: From quantum spin-hall to ordinary phases

Author

Hsu, H.C., Kleftogiannis, I., Guo, G.Y., and Gopar, V.A.

Abstract

Impurities and defects are ubiquitous in topological insulators (TIs) and thus understanding the effects of disorder on electronic transport is important. We calculate the distribution of the random conductance fluctuations P(G) of disordered 2D TI wires modeled by the Bernevig-Hughes-Zhang (BHZ) Hamiltonian with realistic parameters. As we show, the disorder drives the TIs into different regimes: metal (M), quantum spin-Hall insulator (QSHI), and ordinary insulator (OI). By varying the disorder strength and Fermi energy, we calculate analytically and numerically P(G) across the entire phase diagram. The conductance fluctuations follow the statistics of the unitary universality class ß = 2. At strong disorder and high energy, however, the size of the fluctuations dG reaches the universal value of the orthogonal symmetry class (ß = 1). At the QSHI-M and QSHI-OI crossovers, the interplay between edge and bulk states plays a key role in the statistical properties of the conductance.

Published
2018

21. Element-specific magnetic anisotropy determined by transverse magnetic circular x-ray dichroism

Author

Durr, H.A., Guo, G.Y., van der Laan, G., Lee, J., Lauhoff, G., and Bland, J.A.C.

Subjects
Magnetic materials -- Research -- Magnetic properties, Thin films -- Magnetic properties -- Research, Dielectric films -- Magnetic properties -- Research, Nanotechnology -- Research -- Magnetic properties, Science and technology, Magnetic properties, Research
Abstract

Understanding of the magnetocrystalline anisotropy in magnetic materials (the influence of different elemental components on the direction of easy magnetization) can be greatly enhanced by measuring the orbital moment anisotropy of the elemental constituents. A circular x-ray dichroism technique is presented that allows the determination of the microscopic origin of the spin reorientation transition in ultrathin single-crystalline cobalt/nickel films. The stronger anisotropy contribution of a much thinner cobalt layer redirects the easy magnetization direction of the entire film., Understanding of the magnetic anisotropy in nanostructures is of troth scientific and technological importance. In device applications, such as magnetic and magnetooptic recording, the use of different magnetic materials such [...]

Published
1997

22. Ab initio calculation of intrinsic spin Hall conductivity of Pd and Au

Author

Guo, G.Y.

Subjects
Gold -- Magnetic properties, Gold -- Electric properties, Hall effect -- Analysis, Iron alloys -- Electric properties, Iron alloys -- Magnetic properties, Palladium -- Electric properties, Palladium -- Magnetic properties, Platinum -- Magnetic properties, Platinum -- Electric properties, Physics
Abstract

Ab initio relativistic band structure calculation is used for studying spin Hall conductivity (SHC) in Pd and Au metals. The studies have shown that the gigantic spin Hall effect observed in the Au/FePt system is because of the extrinsic mechanisms such as the skew scattering by the impurities in Au.

Published
2009

26. Magnetocrystalline anisotropy of ultrathin Fe films on Ni(110)

Author

Durr, H.A., Guo, G.Y., Thole, B.T, van der Laan, G., and Faculty of Science and Engineering

Subjects
Condensed Matter::Materials Science, Condensed Matter::Superconductivity
Abstract

We determined the magnetic ground-state moments of ultrathin epitaxial Fe films on Ni(110) and found that the overlayer spins orient at an angle of 55 degrees relative to the substrate magnetization direction. This surprising behaviour is a direct consequence of the contribution of orbital magnetic moment to the magnetocrystalline anisotropy.

Published
1996

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