Anisotropic Magnetic Fluctuations in Ferromagnetic Superconductor UGe2: Ge-73-NQR Study at Ambient Pressure

作者：Noma Yuichiro^*; Kotegawa Hisashi; Kubo Tetsuro; Tou Hideki; Harima Hisatomo; Haga Yoshinori; Yamamoto Etsuji; Onuki Yoshichika; Itoh Kohei M; Haller Eugene E; Nakamura Ai; Homma Yoshiya; Honda Fuminori; Aoki Dai

来源：Journal of the Physical Society of Japan, 2018, 87(3): 033704.

DOI：10.7566/JPSJ.87.033704

We report a Ge-73 nuclear quadrupole resonance reinvestigation of the ferromagnetic (FM) superconductor UGe2 at ambient pressure. Careful measurement and analysis of the paramagnetic (PM) spectrum taking into account the calculated electric field gradient (EFG) resulted in modification of the previously reported site assignments for three inequivalent Ge sites. The crossover anomaly at T-x in the FM state is not clearly seen in the temperature dependence of the static internal field at the Ge site, whereas it appears in the nuclear spin-lattice relaxation rate, 1/T-1. A remarkable site dependence of 1/T-1 is observed among the inequivalent Ge sites, where the directions of the principal axes of the EFG are different. This result reveals that the magnetic fluctuation of UGe2 is highly anisotropic, which is consistent with the presence of Ising magnetic fluctuations in the PM state.

• 出版日期2018-3-15