Bachelor thesis report on superconductivity in topological insulator \(Cu_xBi_2Se_3\).

Abstract

Currently, the phenomenon of superconductivity in \(M_xBi_2Se_3\) has been of some interest (particularly \(Cu_xBi_2Se_3\) which is a doped topological insulator). [2] proposed that the inter-orbital odd parity pairing symmetry in a strongly spin orbit coupled normal state might be an explanation for the same. As analysed in [2], this can happen only in the presence of a two component order parameter. However the current understanding still remains inconclusive on some consequences in lieu of this pairing [3], namely that although the pairing is topological, the search for expected Majorana bound states turned out mixed results. It is in this regard that the current thesis aims to study one aspect of this problem, namely, the phenomenon of half quantum vortices present possible in this material.

The thesis is organized as follows: In chapter 1, half quantum vortices (HQV) are analysed using the framework of Ginzburg Landau theory. A concrete realisation is highlighted in form of a microscopic model, done in chapter 2. With the model in hand, the calculation of spin-polarization around vortex states is done. A specific case of overlapping HQV pair (as discussed in Chapter 1) is taken and spin-polarization is computed for the same.

Presentation

Final Report

References

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2. Liang Fu and Erez Berg. “Odd-Parity Topological Superconductors: Theory and Application to CuxBi2Se3”. In: Phys. Rev. Lett. 105 (9 Aug. 2010), p. 097001. doi: 10.1103/PhysRevLett.105.097001. url: https://link.aps.org/doi/10.1103/ PhysRevLett.105.097001.
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