Fig. 1: Magnetic and superconducting phase diagrams of YbRh2Si2 with an in-plane magnetic field.
a, Boundaries of the antiferromagnetic (AFM1 and AFM2) and paramagnetic (PM) phases inferred from calorimetry and magnetoresistance23,24. The back-turn of the critical field HN of AFM1 below 15 mK is well accounted for by a hyperfine field 〈bhf〉 exerted on Yb electrons by Yb nuclear spins, averaged over Yb isotopes24. b–e, Maps of resistance \({\rm{Re}}\,Z(T,H)\) for three samples (b–d) show sample-to-sample variation, in contrast to the reproducible transport signature of the Néel transition (e). For sample D, the measurements are limited by the critical field of the Al contacts. \({\rm{Re}}\,Z(T,H)\) is scaled by the normal-state resistance \({R}_{0}(H)={\rm{Re}}\,Z(11\,{\rm{mK}}, H)\). We identify the observed sharp contours in b–d with superconducting transitions in various parts of the heterogeneous samples (Extended Data Fig. 5). The magnetic phase boundaries (solid green and magenta lines reproduced from a) superimposed onto b–d highlight an abrupt suppression of superconductivity across the AFM1/PM phase boundary and markedly different superconducting behaviour inside the AFM1 and AFM2 phases. f, Superconducting signature of TA in the kinetic inductance \({L}_{\rm{K}}={\rm{Im}}\,Z(T)/\omega\), shown for sample D at H = 0. This feature as a function of field is marked in b–d with open magenta circles. g–j, Contour classes observed in the AFM1 and AFM2 phases across samples B–D and their potential extrapolation beyond the magnetic phase boundaries.
