Possible existence of magnetic polaron in nearly ferromagnetic semiconductor β-US 2

Shugo Ikeda, Hironori Sakai, Naoyuki Tateiwa, Tatsuma D. Matsuda, Dai Aoki, Yoshiya Homma, Etsuji Yamamoto, Akio Nakamura, Yoshinobu Shiokawa, Yuuki Ota, Kiyohiro Sugiyama, Masayuki Hagiwara, Koichi Kindo, Kazuyuki Matsubayashi, Masato Hedo, Yoshiya Uwatoko, Yoshinori Haga, Yoshichika Onuki

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10 Citations (Scopus)


We studied the magnetic properties of the paramagnet β-US 2 with an orthorhombic crystal structure by measuring its magnetization, magnetic susceptibility, specific heat, and electrical resistivity under magnetic field and pressure. The 5f-crystalline electric field (CEF) scheme was determined from the experimental results: a singlet in the ground state and a pseudo-doublet in the first excited state, separated by 85 and 91 K from the ground state. The insulating resistivity markedly changes to a metallic one under a high pressure of 8 GPa similarly to that of the semimetallic Ising-type ferromagnet UTeS with a Curie temperature T C - 87 K. A resistivity anomaly was also observed in the temperature dependence of the resistivity under pressure, most likely corresponding to ferromagnetic ordering. From these experimental results, it was concluded that β-US 2 is in the vicinity of ferromagnetic ordering at ambient pressure. Furthermore, we found that the easy-axis magnetization at low fields for H ∥[001] consists of a linear magnetization based on the 5f-CEF scheme and a ferromagnetic-like magnetization with a saturated moment of 0.042 μB/U. The latter magnetization was analyzed on the basis of the ferromagnetic cluster and discussed from the viewpoint of the magnetic polaron.

Original languageEnglish
Article number114704
JournalJournal of the Physical Society of Japan
Issue number11
Publication statusPublished - 2009 Nov


  • CEF
  • High pressure
  • Magnetic cluster
  • Magnetic polaron
  • USeS
  • UTeS
  • β-US


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