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9 results on '"Zhang, Kunliang"'

4. Majorana flat band edge modes of topological gapless phase in 2D Kitaev square lattice

Author

Zhang, Kunliang, Wang, Peng, and Song, Zhi

Subjects
Condensed Matter - Superconductivity, Quantum Physics
Abstract

We study a Kitaev model on a square lattice, which describes topologically trivial superconductor when gap opens, while supports topological gapless phase when gap closes. The degeneracy points are characterized by two vortices in momentum space, with opposite winding numbers, which are not removable unless meet together. We show rigorously that the topological gapless phase always hosts a partial Majorana flat band edge modes in a ribbon geometry, although such a single band model has zero Chern number as a topologically trivial superconductor. The flat band disappears when the gapless phase becomes topologically trivial, associating with the mergence of two vortices. Numerical simulation indicates that the flat band is robust against the disorder. This finding indicates that the bulk-edge correspondence can be extended to superconductors in the topologically trivial regime as recently proposed in Ref. [PRL 118, 147003 (2017)]., Comment: 12 pages, 4 figures

Published
2018
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7. Angular dependence of remanence of exchange-coupled CoFe/NiO bilayers

Author

Zhao, Tong, Zhang, Kunliang, and Fujiwara, Hideo

Subjects
Hysteresis -- Research, Thin films, Multilayered -- Research, Physics
Abstract

Research into the magnetic properties of Co90Fe10(5 nm)/NiO(1-5 nm) bilayers produced by rf/dc magnetron sputtering is presented. It is concluded that the angular dependence of the remanence of these samples indicates hysteresis around the hard direction, which rises with rising NiO layer thickness.

Published
2001

9. Magnetization reversal of exchange coupled CoFe/IrMn bilayers.

Author

Zhao, Tong, Zhang, Kunliang, and Fujiwara, Hideo

Subjects
*MAGNETIZATION, *MAGNETIC force microscopy
Abstract

The magnetization reversals of circular elements of CoFe/IrMn bilayers were studied using magnetic force microscopy. Drastic changes of domain structures and the nature of the reversal processes were observed with varying thickness of the CoFe layer. The localized incoherent rotation dominates in the reversal process when the CoFe layer is relatively thin while the domain wall motion dominates when the CoFe layer is thick. The effect of the competition between the distributed interfacial ferromagnet/antiferromagnet coupling and the coupling inside the ferromagnetic layer on the nature of the reversal process of the bilayers was investigated. [ABSTRACT FROM AUTHOR]

Published
2002
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