Multiple Superconducting Phases in New Heavy Fermion SuperconductorPrOs4Sb12

Abstract

The superconducting gap structure of recently discovered heavy fermion superconductor PrOs4Sb12 was investigated by using thermal transport measurements in magnetic field rotated relative to the crystal axes. We demonstrate that a novel change in the symmetry of the superconducting gap function occurs deep inside the superconducting state, giving a clear indication of the presence of two distinct superconducting phases with twofold and fourfold symmetries. We infer that the gap functions in both phases have a point node singularity, in contrast to the familiar line node singularity observed in almost all unconventional superconductors.

Gap symmetry of superconducting borocarbide YNi2B2C and skutterudite PrOs4Sb12

“…Among them PrOs 4 Sb 12 is a rather unique case [44,45,46]. Again the angular dependent thermal conductivity data [12,11] suggest i) the presence of two phases denoted A and B and ii) a gap ∆(k) with planar symmetry in A while one with axial symmetry in B phase (see Fig. 6).…”

“…Indeed Izawa et al have shown f-wave sc in Sr 2 RuO 4 [5], d-wave sc in CeCoIn 5 [6] and κ-(ET) 2 Cu(NCS) 2 [7] through the angle dependent magnetothermal conductivity. More recently gap functions ∆(k) in borocarbide YNi 2 B 2 C and skutterudite PrOs 4 Sb 12 are shown to have point nodes and described in terms of s+g-wave sc [8][9][10][11][12]. We show |∆(k)| of these superconductors in Fig.…”

Superconductivity and the high-field ordered phase in the heavy-fermion compound PrOs4Sb12

“…These findings suggest an s-wave, or, perhaps, a Balian-Werthamer p-wave order parameter. On the other hand, the superconducting gap structure of PrOs 4 Sb 12 was investigated by means of thermal conductivity measurements in magnetic fields rotated relative to the crystallographic axes by Izawa et al [8]. These measurements reveal two regions in the H − T plane, a low field region in which ∆(k) has two point nodes, and a high field region where ∆(k) has six point nodes.…”

“…As far as we know, PrOs 4 Sb 12 is the first example of a heavy fermion superconductor based on Pr; all of the other known heavy fermion superconductors are compounds of Ce or U. The superconducting state appears to be unconventional in nature and may consist of two distinct superconducting phases [7,8]. An ordered phase, presumably of magnetic or quadrupolar origin, occurs at high fields > 4.5 tesla and low temperatures < 1.5 K [7,9,10,11,12,13], suggesting that the superconductivity may occur in the vicinity of a magnetic or quadrupolar quantum critical point (QCP).…”

Simultaneous Measurements of Elastic Constant and Resistivity near the Tc of Non-BCS-Type Superconductor PrOs4Sb12

“…The unconventional nature of this superconductivity (SC) has been proven by several studies [2,3]. The gap structure of the SC phase has been studied in the last decade, it has, however, not yet been fully understood [4,5].…”