Magnetic Properties under Pressure in Novel Spin-Triplet Superconductor UTe2
Dexin Li, Ai Nakamura, Fuminori Honda, Yoshiki J. Sato, Yoshiya Homma, Yusei Shimizu, Jun Ishizuka, Youichi Yanase, G. Knebel, J. Flouquet, Dai Aoki
Abstract
We report the magnetic susceptibility and the magnetization under pressures up to 1.7 GPa above the critical pressure, Pc ~ 1.5 GPa, for H || a, b, and c-axes in the novel spin triplet superconductor UTe2. The anisotropic magnetic susceptibility at low pressure with the easy magnetization a-axis changes to the quasi-isotropic behavior at high pressure, revealing a rapid suppression of the susceptibility for a-axis, and a gradual increase of the susceptibility for the b-axis. At 1.7 GPa above Pc, magnetic anomalies are detected at TMO ~ 3K and TWMO ~ 10 K. The former anomaly corresponds to long-range magnetic order, most likely antiferromagnetism, while the latter shows a broad anomaly, which is probably due to the development of short range order. The unusual decrease and increase of the susceptibility below TWMO for H || a and b-axes, respectively, indicate the complex magnetic properties at low temperatures above Pc. This is related to the interplay between multiple fluctuations dominated by antiferromagnetism, ferromagnetism, valence and Fermi surface instabilities.