73Ge-nuclear magnetic resonance/nuclear quadrupole resonance investigation of magnetic properties of URhGe

Abstract

We report on the 73Ge-nuclear magnetic resonance (NMR)/nuclear quadrupole resonance (NQR) results for the ferromagnetic (FM) superconductor URhGe. The magnitude and direction of the internal field, Hint, and the parameters of the electric field gradient at the Ge site were determined experimentally. By using powdered polycrystalline samples oriented by different methods, the field dependences of NMR shift and nuclear spin relaxation rates for H0 ∥ c (easy axis) and H0 ∥ b were obtained. From the NMR shifts for H0 ∥ b, we confirmed a gradual suppression of the Curie temperature and observed a phase separation near the spin reorientation. The observation of the phase separation gives microscopic evidence that the spin reorientation under H0 ∥ b is of first order at low temperatures. The nuclear spin-lattice relaxation rate 1/T1 indicates that the magnetic fluctuations are suppressed for H0 ∥ c, whereas the fluctuations remain strongly for H0 ∥ b. The enhancements of both 1/T1T and the nuclear spin-spin relaxation rate 1/T2 for H0 ∥ b toward the spin reorientation field suggest that the field-induced superconductivity in URhGe emerges under the magnetic fluctuations along the b- and c-axes.