Ferromagnetic superconductivity mediated by pressure-enhanced spin fluctuation developed around the phase boundary of FM1 and FM2 in UGe

ウラン系強磁性超伝導物質UGeにおけるFM1とFM2の相境界近傍で発達する磁気的ゆらぎと超伝導について

立岩 尚之   ; 芳賀 芳範   ; 山本 悦嗣  

Tateiwa, Naoyuki; Haga, Yoshinori; Yamamoto, Etsuji

ウラン系強磁性超伝導物質UGeの動的磁性に関する研究を行った。高橋らのスピンのゆらぎ理論を用いて磁化データを解析し、スピンのゆらぎのスペクトルの分布幅, を求めた。両方とも超伝導が現れる圧力領域で異常な増大を示す。この結果は、強磁性相FM1, FM2の相境界で発達する磁気的なゆらぎが超伝導出現に主要な役割を果たすことを意味する。

We study the dynamical magnetic property under high pressure in uranium ferromagnetic superconductor UGe from the analysis of magnetic data with Takahashi's spin fluctuation theory. We determined the pressure dependencies of spin fluctuation parameters and , the widths of the spin fluctuation spectrum in the energy and the momentum spaces, respectively. and show anomalous behavior around pressure region where the superconductivity appears. We suggests that the superconductivity in UGe is mediated by pressure-enhanced spin fluctuation developed around the phase boundary of two ferromagnetic phases FM1 and FM2.