THESIS
2013
xx, 80 pages : illustrations (some color) ; 30 cm
Abstract
This thesis is divided into two parts. In the rst part we show that a quasi-one-dimensional d
x2
-y2-wave superconductor with Rashba spin-orbit coupling is
a DIII class, time-reversal invariant, topological superconductor (TS) which supports
a Majorana Kramers Doublet (MKD) at each end of the TS. A MKD is a pair of Majorana end states (MESs) protected by time-reversal symmetry (TRS).
An external magnetic field breaks TRS and drives the system from DIII to D class in which case a single MES appears at each end of the TS. We show that a MKD induces resonant Andreev reflection with zero bias conductance peak of 4e
2/h. Experimental realizations of the proposed model are discussed. In the
second part we show that an in-plane magnetic field can drive a fully gapped p ± ip topological supe...[
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This thesis is divided into two parts. In the rst part we show that a quasi-one-dimensional d
x2
-y2-wave superconductor with Rashba spin-orbit coupling is
a DIII class, time-reversal invariant, topological superconductor (TS) which supports
a Majorana Kramers Doublet (MKD) at each end of the TS. A MKD is a pair of Majorana end states (MESs) protected by time-reversal symmetry (TRS).
An external magnetic field breaks TRS and drives the system from DIII to D class in which case a single MES appears at each end of the TS. We show that a MKD induces resonant Andreev reflection with zero bias conductance peak of 4e
2/h. Experimental realizations of the proposed model are discussed. In the
second part we show that an in-plane magnetic field can drive a fully gapped p ± ip topological superconductor into a gapless phase which supports Majorana flat bands (MFBs). Unlike previous examples, the MFBs in the gapless
regime are protected from disorder by a chiral symmetry. We show that the Majorana fermions associated with the MFBs induce nearly quantized zero bias conductance peak in tunnelling experiments. The consequences of broken chiral
symmetry are discussed.
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