Bulk superconductivity in undoped T′-La1.9Y0.1CuO4 probed by muon spin rotation

K. M. Kojima; Y. Krockenberger; I. Yamauchi; M. Miyazaki; M. Hiraishi; A. Koda; R. Kadono; R. Kumai; H. Yamamoto; A. Ikeda; M. Naito

doi:10.1103/PhysRevB.89.180508

Bulk superconductivity in undoped T′-La1.9Y0.1CuO4 probed by muon spin rotation

K. M. Kojima, Y. Krockenberger, I. Yamauchi, M. Miyazaki, M. Hiraishi, A. Koda, R. Kadono, R. Kumai, H. Yamamoto, A. Ikeda, M. Naito

DOI 10.1103/PhysRevB.89.180508 · Physical Review B

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Abstract

The Meissner effect has been directly demonstrated by depth-resolved muon spin rotation measurements in high-quality thin films of the T′-structured cuprate, T′-La1.9Y0.1CuO4, to confirm bulk superconductivity (Tc≃21 K) in its undoped state. The gradual expelling of an external magnetic field is observed over a depth range of ∼100 nm in films with a thickness of 275(15) nm, from which the penetration depth is deduced to be 466(22) nm. Based on this result, we argue that the true ground state of the “parent” compound of the n-type cuprates is not a Mott insulator but a strongly correlated metal with colossal sensitivity to apical oxygen impurities.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
La1.9Y0.1CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	21	Pressure not reported	unknown
La1.9Y0.1CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	21	Pressure not reported	unknown