Ferromagnetic quantum critical point in a Ni_1-xRh_x alloy with x = 0.375

A chemical substitution-induced ferromagnetic quantum critical point in polycrystalline Ni_1−xRh_x alloys. Non-Fermi liquid behavior is observed close to the critical concentration x_crit = 0.375, where the Curie temperature vanishes. The electronic specific heat C_el/T, the volume thermal expansion coefficient α_V/T, and the Grüneisen ratio Γ ≡ α_V/C_el diverge logarithmically upon cooling to absolute zero, providing strong evidence of a ferromagnetic quantum critical point in Ni_1−xRh_x [1]. We further perform a hyperscaling analysis of the thermodynamic measurements as a function of temperature and magnetic field for Ni_1−xRh_x with x_crit = 0.375. The obtained critical exponents agree well with the theory proposed by Belitz, Kirkpatrick, and Vojta for a disorder tuned quantum critical point in the preasymptotic region [2].

[1] C.-L. Huang et al., Phys. Rev. Lett. 124, 117203 (2020).

[2] R.-Z. Lin and C.-L. Huang, Phys. Rev. B 105, 024429 (2022).