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Obana, Tetsuhiro*; Murakami, Haruyuki; Takahata, Kazuya*; Hamaguchi, Shinji*; Chikaraishi, Hirotaka*; Mito, Toshiyuki*; Imagawa, Shinsaku*; Kizu, Kaname; Natsume, Kyohei; Yoshida, Kiyoshi
Physica C, 518, p.96 - 100, 2015/11
Times Cited Count：7 Percentile：31.9(Physics, Applied)Ota, Yukihiro; Nagai, Yuki; Machida, Masahiko
Physica C, 518, p.5 - 9, 2015/11
Times Cited Count：0 Percentile：0(Physics, Applied)Topological superconductors are notable materials, owing to the mathematical interest as topological matter and the application potential of quantum engineering. To clarify their characters relying on gap-function types, we build up a low-energy effective theory, focusing on a model of superconductor Cu
BiSe
. The non-magnetic impurity effects in our previous numerical study indicates that the system has both p-wave and s-wave aspects. A perturbation study is insightful for explaining this peculiar behavior. Since the normal electrons are dominated by the Dirac-type dispersion relation, we assign a low-energy case as a large-Dirac-mass one. When the system has an odd-parity fully-gapped pair potential, our approach indicates that the effective gap function in the low-energy domain has not only a chiral p-wave-like component, but also an s-wave-like one. This peculiar mixture of p-wave and s-wave leads to intriguing responses in the present model.
Higashi, Yoichi*; Nagai, Yuki; Yoshida, Tomohiro*; Kato, Masaru*; Yanase, Yoichi*
Physica C, 518, p.1 - 4, 2015/11
Times Cited Count：0 Percentile：0(Physics, Applied)We study the excitation spectra and the wave functions of quasiparticle bound states at a vortex and an edge in bilayer Rashba superconductors under a magnetic field. In particular, we focus on the quasiparticle states at the zero energy in the pair- density wave state in a topologically non-trivial phase. We numerically demonstrate that the quasiparticle wave functions with zero energy are localized at both the edge and the vortex core if the magnetic field exceed the critical value.
Nagai, Yuki; Nakamura, Hiroki; Machida, Masahiko
no journal, ,
The discovery of topological superconductors opened a new research avenue on superconducting states. The topologically-protected nature results in gapless zero-energy quasi-particles identified as the Majorana fermions at surface edges, while the superconducting gap opens in the bulk. The experimental works on topological insulators have recently revealed that Bi
Se and SnTe turn into superconductors with carrier doping. Their superconducting gap functions are not conventional, since zero-bias conductance peaks (ZBCP's) have been detected by the point contact spectroscopy. ZBCP's can be regarded to originate from their non-trivial topology. The Majorana fermion appears at not only surface edges but also vortex cores in topological superconductors. We reveal that Majorana quasiparticle bound states inside the vortex core are spin-polarized by solving the massive Dirac Bogoliubov-de Gennes equations considering the spin-orbit coupling. This results is universal for "Dirac superconductivity" whose rotational degree of freedom is characterized by the total angular momentum J = S + L. Spin-sensitive probes such as the neutron scattering and other measurements above the first critical magnetic field can easily detect the spin-polarized vortex core.
