Non-magnetic to magnetic transition under high pressure in narrow-gap semiconductor -US

Tateiwa, Naoyuki   ; Haga, Yoshinori   ; Sakai, Hironori   ; Ikeda, Shugo*; Matsuda, Tatsuma; Yamamoto, Etsuji  ; Onuki, Yoshichika*

We have measured the magnetization of an uranium chalcogenide compound -US under high pressure by piston cylinder and indenter type cells up to 2.42 GPa in a commercial SQUID magnetometer. The compound is a narrow-gap semiconductor that does not order magnetically down to 0.3 K at 1 bar. In this study, it was found that a ferromagnetic state is induced above 1 GPa. The pressure phase diagram were obtained. The values of the spontaneous magnetic moment at 0 K are less than 0.1 , suggesting that the pressure-induced phase is a very weak ferromagnetic state. Considering the CEF singlet ground state in -US, it is suggest that the ferromagnetic state is an "induced-magnetic phase" often observed in some praseodymium compounds such as PrTl. The experimental results are discussed in terms of the mean field theory.