Strong magnetic field enhancement of spin triplet pairing arising from coexisting2kFspin and2kFcharge fluctuations

Abstract

We study the effect of the magnetic field ͑Zeeman splitting͒ on spin triplet superconductivity. We show generally that the enhancement of spin triplet pairing mediated by coexisting 2k F spin and 2k F charge fluctuations can be much larger than in the case of triplet pairing mediated by ferromagnetic spin fluctuations. We propose that this may be related to the recent experiment on ͑TMTSF͒ 2 ClO 4 , in which the possibility of a singlet to triplet pairing transition has been suggested.

Low-Field Superconducting Phase of(TMTSF)2ClO4

“…OTE states have previously been discussed in the context of disordered 2D electron systems [42]. For a quasi-1D system such as we have here, a field-induced transition from OSO to OTE pairing is found in theoretical studies based on the extended Hubbard model, due to enhancement of charge fluctuations over spin fluctuations [43][44][45]. The two possible H-SC states could be distinguished by studying the effect of disorder on T c within the H-SC phase, but such studies to date have only measured the L-SC phase [36,37].…”

Competition between triplet, singlet and FFLO states in organic superconductors (TMTSF)2X under magnetic field

“…[10,11,12] Applying the magnetic field strongly enhances the spin triplet f -wave pairing with S z = 1, so that even if the condition is not satisfied, the triplet pairing still has a chance of taking place for large magnetic field. [13] Bearing these in mind, we move on to the calculation results, where t x = 1.0, t y = 0.2 and U = 1.7 are fixed on the 1024×64 sites. Note that λ in the FFLO state takes maximum value with the Q c = (Q cx , 0) in this study.…”

“…Recently, we have further found that the triplet pairing mediated by 2k F spin+2k F charge fluctuations is strongly enhanced by the field, which supports the possibility of singlet-triplet transition in (TMTSF) 2 X under magnetic field. [13] In the present study, we investigate the possibility of the FFLO state from the microscopic point of view by applying random phase approximation(RPA) to a model for (TMTSF) 2 X. We investigate the competition between triplet, singlet and the FFLO state, and propose the …”

Large triplet pairing mixing in the FFLO state of spin fluctuation mediated superconductivity in Q1D systems

“…The coexistence of the charge fluctuations and the spin fluctuations is supported from the fact that diffuse X-ray scattering experiments observe the coexistence of 2k F charge density wave (CDW) and the 2k F spin density wave (SDW) in the vicinity of the superconducting phase in (TMTSF) 2 PF 6 [12,13]. Moreover, we have recently found that this kind of triplet pairing due to the coexistence of 2k F spin + 2k F charge fluctuations is strongly enhanced by the magnetic field [14].…”