Anisotropic field response of specific heat for a ferromagnetic superconductor UCoGe in magnetic fields

Abstract

Magnetic-field-angle-resolved specific heat and magnetization measurements were conducted on a ferromagnetic superconductor UCoGe with remarkable anisotropic upper critical field Hc2. Although Hc2 reaches a high magnetic field (∼20T) along the b axis, it is small (∼0.6T) when a magnetic field is applied along the magnetic easy c axis. This study indicates that the specific heat is abruptly suppressed when the magnetic field is applied toward the c axis from the a and b axes in the ferromagnetic state. The field response of density of states (DOS) is anisotropic, relative to the c axis, and its angle dependence is slightly singular. The Ising-type magnetic anisotropy of the ferromagnetic state is dominant even in the anisotropic reinforced superconducting state. These facts indicate that the suppression of DOS may closely relate to the superconducting state. We theoretically analyze these findings together with URhGe and UTe2 by highlighting the common and distinctive features among three compounds.

Source-reported materials — not catalogue approval

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