Pressure effect on the competition between ferromagnetic and antiferromagnetic spin fluctuations in TmTe investigated by [formula omitted]-NMR

Abstract

To elucidate from a microscopic point of view the initial evolution of spin fluctuations in TmTe from the semiconducting state at ambient pressure with an antiferroquadrupole ordering ( T Q = 1.8 K ) to the intermediate-valence metallic state at high pressures P ⩾ 2 GPa with a ferromagnetic (FM) ordering ( T C ≃ 14 K ) , we have carried out 125 Te-NMR study at pressures P = 0 and 0.9 GPa. The spin-lattice relaxation rate measurements revealed a pronounced increase of the staggered susceptibility below T * ≃ 14 K , in addition to the Curie-Weiss-type increase of the uniform susceptibility. Below ∼ T * , a wipe-out decrease of the NMR intensity and the finding of an unconventional NMR signal around ∼ 10 MHz that is insensitive to applied field lead to the conclusion that a field-induced short-range FM ordering caused by the competition of FM and antiferromagnetic fluctuations takes place. Pressure of 0.9 GPa hardly affects the anomalous NMR behaviors below ∼ T * , leading to speculate that the short-range FM ordering in the semiconducting state shares the origin with the long-range FM ordering at ≃ 14 K in the high-pressure metallic state.