Possible unconventional surface superconductivity in the half-Heusler compound YPtBi

Eylon Persky; Alan Fang; Xinyang Zhang; Carolina Adamo; Phillip Wu; Eli Levenson-Falk; Chandra Shekhar; Claudia Felser; Binghai Yan; Aharon Kapitulnik

doi:10.1103/qt3v-yypc

Possible unconventional surface superconductivity in the half-Heusler compound YPtBi

Eylon Persky, Alan Fang, Xinyang Zhang, Carolina Adamo, Phillip Wu, Eli Levenson-Falk, Chandra Shekhar, Claudia Felser, Binghai Yan, Aharon Kapitulnik

DOI 10.1103/qt3v-yypc · Physical Review B

T1

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Abstract

We report an extensive study of the noncentrosymmetric half-Heusler superconductor YPtBi, revealing an unusual relation between bulk superconductivity and the possible appearance of surface superconductivity on the (111) oriented surface, at temperatures up to three times the bulk transition temperature. Transport measurements confirmed the low carrier density of the material and its bulk superconducting transition, which was also observed in ac susceptibility through mutual inductance (MI) measurements. However, a weak signature of superconductivity in the MI measurements appeared much above the bulk transition temperature, which was further observed in scanning tunneling spectroscopy, pointing to a possible surface superconducting state. Polar Kerr effect measurements suggest that while the bulk superconductor may exhibit an unusual nodal superconducting state, only the surface state breaks time reversal symmetry. Complementary tunneling measurements on LuPtBi are used to establish the observations on YPtBi, while density-functional theory calculations may shed light on the origin of this unusual surface state.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
YPtBi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	0.8	Pressure not reported	unknown
LuPtBi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1	Pressure not reported	unknown
YPtBi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2.64	Pressure not reported	onset
YPtBi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3	Pressure not reported	onset
LuPtBi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	5	Pressure not reported	onset
BiPt Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.3	Pressure unresolved	unknown
Bi2Pt Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	2	5.5 GPa	unknown
YBi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	5	2.6 GPa	unknown
LuBi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	5.75	3 GPa	unknown