일본 Osaka Prefecture University의 Yoichi Higashi박사님을 초청하여 아래와 같이 세미나를 개최합니다.

학과 구성원 여러분의 많은 참석을 부탁 드립니다. 

         아             래  

     1. 일시: 2015년 3월 16일(월) 오후 12시 – 1시 

     2. 장소: 물리학과 2층 라운지 세미나실

     3. 초청연사: Yoichi Higashi 박사님 (Osaka Prefecture University)

     4. 제목: Robust zero-energy bound states around a pair-density-wave vortex core in locally noncentrosymmetric superconductors 

     5. Abstract: We numerically investigate the electronic structures around a vortex core in a bilayer superconducting system, with s-wave pairing, Rashba spin-orbit coupling and Zeeman magnetic field, with use of the quasiclassical Green's function method [1]. There are the Bardeen-Cooper-Schrieffer (BCS) phase and the so-called pair-density wave (PDW) phase in the temperature-magnetic field phase diagram in a bulk uniform system [2]. In the low magnetic field perpendicular to the layers, the zero energy vortex bound states in BCS phase is split by the Zeeman magnetic field. In the high magnetic field, the PDW state appears, whose sign of the order parameter is different between the layers. We find that the vortex core suddenly shrinks and the zero-energy bound states appear at the BCS-PDW transition magnetic field. We discuss the origin of this different vortex core structure between the BCS and PDW states from the relation between the vortex bound states and the superconducting gap structure in the bulk energy spectra. The strong spin-orbit coupling even in the high magnetic field stabilizes the PDW state and zero-energy vortex bound states in this state. These characteristic behaviors in the PDW state can be observed by scanning tunneling microscopy/spectroscopy.

[1] Y. Higashi et al., J. Phys.: Conf. Ser. 568, 022018 (2014).

[2] T. Yoshida et al., Phys. Rev. B 86, 134514 (2012).