Shimizu Y, Kittaka S, Sakakibara T, Haga Y, Yamamoto E, Amitsuka H, Tsutsumi Y, Machida K. Field-orientation dependence of low-energy quasiparticle excitations in the heavy-electron superconductor UBe(13).
PHYSICAL REVIEW LETTERS 2015;
114:147002. [PMID:
25910153 DOI:
10.1103/physrevlett.114.147002]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Indexed: 06/04/2023]
Abstract
Low-energy quasiparticle excitations in the superconducting (SC) state of UBe_{13} were studied by means of specific-heat (C) measurements in a rotating field. Quite unexpectedly, the magnetic-field dependence of C(H) is linear in H with no angular dependence at low fields in the SC state, implying that the gap is fully open over the Fermi surfaces, in stark contrast to previous expectations. In addition, a characteristic cubic anisotropy of C(H) was observed above 2 T with a maximum (minimum) for H∥[001] ([111]) within the (11[over ¯]0) plane, in the normal as well as in the SC states. This oscillation possibly originates from the anisotropic response of the heavy quasiparticle bands, and might be a key to understand the unusual properties of UBe_{13}.
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