Anomalous transport phenomena inpx+ipysuperconductors

Abstract

Spontaneous breaking of time-reversal symmetry in superconductors with the px + ipy symmetry of the order parameter allows for a class of effects which are analogous to the anomalous Hall effect in ferromagnets. These effects exist below the critical temperature, T < Tc. We develop a kinetic theory of such effects. In particular, we consider anomalous Hall thermal conductivity, the polar Kerr effect, the anomalous Hall effect, and the anomalous photo-and acousto-galvanic effects.Introduction: One of the leading candidates for pwave pairing in electronic systems is Sr 2 RuO 4 . Numerous experiments indicate that the superconducting state of Sr 2 RuO 4 has odd parity, breaks time reversal symmetry and is spin triplet.1-6 The order parameter consistent with these experiments is given by the chiral p-wave state 7 which is an analog of the 3 He-A-phase. The Fourier transform of the real space order parameter ∆ αβ (r − r ) has the form ∆ αβ (p) ∼ (p x ± ip y )S · σ αβ , where S is the spin of the Cooper pair, σ are the Pauli matrices, and α and β are spin indices. However, the observation of power law temperature dependence of specific heat 8 and NMR, 9 the absence of electric currents along edges, 10 and the absence of a split transition in the presence of an in-plane magnetic field 11 are inconsistent with the theoretically expected properties of a simple chiral superconductor. Consideration of additional experimental manifestations of spontaneous breaking of time-reversal symmetry in p x + ip y superconductors may clarify the nature of superconducting state in Sr 2 RuO 4 .

Floquet topological phases with fourfold-degenerate edge modes in a driven spin-1/2 Creutz ladder

“…In early studies, it was already identified that for certain values of the magnetic flux, the model belongs to the symmetry class AIII and there are chiral symmetry protected edge modes at the boundaries of the ladder [67]. In later investigations, various modified versions of the CL are proposed [69][70][71][72][73][74][75][76][77][78][79], and also realized experimentally in atom-optical setups like photonic lattices [80,81] and cold atoms [82,83]. Intriguing topological features of the CL are reflected in the formation of AB cages [81] and the quantized Thouless pumping [84].…”

Kerr Effect from Diffractive Skew Scattering in Chiral px±ipy Superconductors

“…[27] Therefore, the observed finite Kerr effect was considered within clean multiband models [28][29][30][31][32] and single band models with impurities. [26,33,34] Notwithstanding the significant theoretical interested, to the best of our knowledge the effect of diffractive skew scattering from quantum impurity complexes has been disregarded in the literature, so far. It will therefore be the subject of the present paper.…”

“…However, each of these two extrinsic mechanisms implies different dependence on impurity concentration as n imp and n 2 imp respectively. The most recent full T -matrix analysis [34] uncovered that skew scattering of low-energy quasiparticle on strong impurities results in anomalous Hall response being linearly proportional to τ ∝ n −1 imp and falling off linearly with inverse frequency. The kinetic approach of Ref.…”

“…The kinetic approach of Ref. [34] is however limited to low frequencies, Ω < ∆ 0 . Further-more, since quasiparticle density decreases exponentially fast with temperature, this mechanisms dominates Kerr rotation only in the immediate vicinity of the critical temperature T c − T T c .…”

Topological properties of a generalized spin–orbit-coupled Su–Schrieffer–Heeger model

“…Also, one-dimensional (1D) systems, for instance, Su-Schrieffer-Heeger (SSH) chain [11] in the presence of sublattice and/or spin degrees of freedom are capable of exhibiting nontrivial phases providing topological insulators [12][13][14][15][16][17][18]. In this framework, several theoretical works have been dedicated to investigating effects of spin-orbit coupling [19], Zeeman magnetic field [20,21], and curvature [22] on topological properties of 1D superlattices by characterizing phase transition points [23]. In addition, a new type of artificial quantum matter lattice composed of multilayer heterostructures of topological insulators and ordinary insulators has been fabricated experimentally which is condensed matter realization of SSH model [24].…”