p-wave superconductivity in iron-based superconductors

Abstract

The possibility of p-wave pairing in superconductors has been proposed more than five decades ago, but has not yet been convincingly demonstrated. One difficulty is that some p-wave states are thermodynamically indistinguishable from s-wave, while others are very similar to d-wave states. Here we studied the self-field critical current of NdFeAs(O,F) thin films in order to extract absolute values of the London penetration depth, the superconducting energy gap, and the relative jump in specific heat at the superconducting transition temperature, and find that all the deduced physical parameters strongly indicate that NdFeAs(O,F) is a bulk p-wave superconductor. Further investigation revealed that single atomic layer FeSe also shows p-wave pairing. In an attempt to generalize these findings, we re-examined the whole inventory of superfluid density measurements in iron-based superconductors and show quite generally that single-band weak-coupling p-wave superconductivity is exhibited in iron-based superconductors.

Classifying superconductivity in an infinite-layer nickelate Nd0.8Sr0.2NiO2

“…Deduced (0) = 740 ± 3 nm is similar to (0) = 690-850 nm measured for samples possessing maximal Tc values for cuprate counterpart La1-xSrxCuO2 [37]. By utilizing deduced (0) value the Ginzburg-Landau parameter = λ(0) (0) = 130 which is similar to La1-xSrxCuO2 [33,37] and this value is at the upper-level range for other cuprates and unconventional superconductors [15,23,24,26,[38][39][40][41][42][43]. Table I.…”

“… is the angle around the Fermi surface subtended at (, ) in the Brillouin zone (details can be found elsewhere [22,25,26]). In Eq.…”

“…where ( ) = ; polar configuration (15) ( ) = √1 − 2 ; axial configuration (16) More details about the Jc(sf,T) analysis for p-wave symmetry can be found elsewhere [26,27]. This approach is recently applied for wide range of thin film unconventional superconductors [23,24,[26][27][28][29][30][31][32].…”

Classifying superconductivity in ThH-ThD superhydrides/superdeuterides

“…Semenok et al [44] reported the discovery of a high-temperature superconducting phase of ThH 9 at P=170 GPa which exhibits P6 3 /mmc crystallographic symmetry and superconducting transition temperature of T c =146 K. They also performed first principles calculations and deduced the effective mass in this superconductor: As we mentioned in our previous papers [12,13,46,47], first principles calculations [39,48,49] always provide α-values near 5, which is the very strong-coupling limit for s-wave symmetry (also note that other superconducting gap symmetries have weak-coupling limits of α∼5 [50][51][52]). Despite the orthodox view, several new, alternative, approaches were developed to explain NRT superconductivity in compressed hydrides: Hirsch and Marsiglio [53], Souza and Marsiglio [54], Harshman and Fiory [55], as well as Kaplan and Imry [56].…”

Classifying superconductivity in Moiré graphene superlattices

“…where m(T) is the is the maximum amplitude of the k-dependent d-wave gap given by Eq. 9,  is the angle around the Fermi surface subtended at (, ) in the Brillouin zone (details can be found elsewhere [58,59]). In Eq.…”