Emergent physics at the oxide heterointerface

Abstract

A series of emergent phenomena, unfolding at surprising regularity in oxide het-
erointerfaces, have captivated a sizeable section of the science community. The
highly conductive two-dimensional electron liquid at the heterointerface between
two insulating oxides exhibits finite-momentum superconductivity coexisting with
inhomogeneous ferromagnetism, gate-voltage-induced SITs and MITs, as well as a
complex excitation spectrum. We find [1] the role of disorder on superconductivity
and ferromagnetism at the interface to be important as the system breaks up into
segregated regions of superconductivity and ferromagnetism, ruling out an FFLO
state. The unusual coexistence of superconductivity and ferromagnetism at the in-
terface may have its origin in disorder while O-site vacancy suppresses anti-site dis-
order and releases the lattice mismatch strain [2]. A perpendicular magnetic field
leads to topological superconductivity and possible gapless excitations [3] such as
Majorana fermions, at the core of a vortex, which are vulnerable to disorder. The
surprising observation of transient superconductivity above the nominal Tc implies
a 'hidden' superconducting order [4]. Such a hidden superconducting state [5] and
its BKT nature have also been investigated [6]. The Lifshitz transition turns out to be
more prominent in the Seebeck coefficient instead of the Hall number [7].

[1] N. Mohanta, A. Taraphder, J. Phys. Cond. Mat. 26, 025705 (2014); ibid 26, 215703 (2014).
[2] Urmimala Dey, Swastika Chatterjee and A. Taraphder, to be published.
[3] N. Mohanta and A. Taraphder, Europhys. Lett. 108, 60001 (2014).
[4] Shelender Kumar, Gopi Nath Daptary, Pramod Kumar, Anjana Dogra, N. Mohanta, A.
Taraphder, R. C. Budhani, Aveek Bid, Phys. Rev. B. 95, 174502 (2017).
[5] N. Mohanta and A. Taraphder, Phys. Rev. B. 92, 174531 (2015).
[6] G. N. Daptary, et al., Phys. Rev. B. 94, 085104 (2016).
[7] S. Nandy, N. Mohanta, S. Acharya, A. Taraphder, Phys. Rev. B 94, 155103 (2016).
[8] S. Nandy, et al., to be published.

Host: R. Sarkar

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