Large and homogeneous mass enhancement in the rattling-induced superconductor KOs2O6

Taichi Terashima; Nobuyuki Kurita; Andhika Kiswandhi; Eun-Sang Choi; James S. Brooks; Kota Sato; Jun-ichi Yamaura; Zenji Hiroi; Hisatomo Harima; Shinya Uji

doi:10.1103/PhysRevB.85.180503

Large and homogeneous mass enhancement in the rattling-induced superconductor KOs2O6

Taichi Terashima, Nobuyuki Kurita, Andhika Kiswandhi, Eun-Sang Choi, James S. Brooks, Kota Sato, Jun-ichi Yamaura, Zenji Hiroi, Hisatomo Harima, Shinya Uji

DOI 10.1103/PhysRevB.85.180503 · Physical Review B

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Abstract

We have determined the Fermi surface in KOs2O6 (Tc=9.6 K and Bc2∼32 T) via de Haas–van Alphen (dHvA) oscillation measurements and a band structure calculation. We find effective masses up to 26(1)me (me is the free electron mass), which are unusually heavy for compounds where the mass enhancement is mostly due to electron-phonon interactions. Orbit-resolved mass enhancement parameters λdHvA are large but fairly homogeneous, concentrated in the range 5–8. We discuss origins of the large homogeneous mass enhancement in terms of rattling motion of the K ions.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
KOs2O6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	9.6	Pressure not reported	unknown
RbOs2O6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	6.3	Pressure not reported	unknown
CsOs2O6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	3.3	Pressure not reported	unknown