Magnetic-field induced s+if pairing in Ising superconductors

Abstract

We show that an in-plane Zeeman field applied to non-centrosymmetric Ising superconductors converts singlet s-wave Cooper pairs to equal-spin triplet if pairs, leading to an enhancement of the critical transition line beyond expected from Ising spin-orbit coupling. Singlet to triplet conversion relates to a phase transformation due to spin rotation by the Zeeman field and has a geometric origin. The discussion is especially relevant, but not limited to monolayer transition metal dichalcogenides.

Ising pairing in atomically thin superconductors

“…As already alluded to, triplet pairing is another intriguing property that may accompany Ising superconductivity. Möckli and Khodas [31,32] suggested that the superconducting state in monolayer TMD becomes parity mixed with triplet pairing-particularly the f -wave. The mixing of singlet and triplet pairing in monolayer NbSe 2 was also confirmed by Wickramaratne et al [34] through density functional theory (DFT) calculations.…”

“…A c c e p t e d M a n u s c r i p t points [23,24]. Further theoretical work not only outlines a broader material pool of potential Ising superconductors but also suggests a possible realization of topological superconductivity in these systems [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. This mini-review aims at providing a progress report of atomically thin superconductors with enhanced B c2 that are mostly attributed to Ising pairing (Fig.…”

Ionic gating in the study of superconductivity

“…伊辛超导体在过渡金属硫族化物中具有普适性, 除了MoS 2 [41,62] , Xi等人 [61] , 并得到了Lv等人 [65] 在理论上的支 持和拓展. Möckli和Khodas [66] 认为面内平行磁场将s波 转变为同位旋的f 波, 最终得到s+if非常规超导. Liu [67] , Nakamura和Yanase [68] [76,77] , YBCO [78,79] , La 2 -CuO 4+δ [80] , Pr 2 CuO 4+δ [81] 和NdBaCu 3 O 7 [82] , 以及电子掺 杂的Pr 2−x Ce x CuO 4 [83,84] 和La 2−x Ce x CuO 4 [85,86] .…”

Ising superconductors: Interplay of magnetic field, triplet channels, and disorder

“…To illustrate this, we work with two basis function examples: (i)γ(k) = sgn[γ(k)], for which γ 2 (k) → ∆ 2 so and γ 2 (k) = 1. This toy example is extensively used throughout the literature and in some situations gives qualitatively correct results [21,23,35]; (ii) γ(k) = √ 2 cos(3ϕ k ), which implements a more realistic SOC for the point group D 3h . The case (i) is frequently used for multi-pocket Fermi surfaces, while case (ii) is suitable for simply connected Fermi surfaces.…”

“…The imaginary i is the total Berry phase accumulated by the spins in the course of realignment, see Ref. [23].…”