Probing Larkin-Ovchinnikov Superconductors via Junction-Dependent Effects of Band-Hybridized Andreev Midgap States
* SPEAKERS
Name
Affiliation
E-mail
Prof. Qinghong Cui
Qujing Normal University
Prof. Xin Wan(APCTP) xinwan(at)apctp.org
* HOST(Applicant)
Name
Affiliation
E-mail
-
* DATE / TIME
2010-07-20, 04:00pm
* PLACE
Conference room 503, APCTP Headquarters, Pohang, Korea
* ABSTRACT
When a spin-singlet superconductor is subject to a Zeeman (or exchange) field, the Fermi surfaces of spin-up and -down electrons are split apart, thus causing some Cooper pairs of the BCS state to break up. Fulde and Ferrell (FF) and Larkin and Ovchinnikov (LO) proposed separately that a new superconducting state with periodic spatial variation of the order parameter (OP) can become more stable than the BCS state if the Zeeman field is sufficiently strong. Even though experimental indications of the existence of the FFLO state have been reported in various superconductors, direct evidence of the spatial variation of the OP is still desirable. Here we show that a hybridized midgap-states band, which is formed inside the gap of an s-wave FFLO superconductor as a result of the periodic sign reversal of the OP, can give rise to different distinctive features in the point-contact and tunneling limits of the conductance spectroscopy of a normal metal/superconductor junction, when the periodic variation of the OP is parallel with the junction interface. These features can serve as strong signatures of the FFLO state.
