High-field moment polarization in the ferromagnetic superconductor UCoGe

強磁性超伝導体UCoGeの高磁場モーメント分極

Knafo, W.*; 松田 達磨; 青木 大*; Hardy, F.*; Scheerer, G. W.*; Ballon, G.*; Nardone, M.*; Zitouni, A.*; Meingast, C.*; Flouquet, J.*

Knafo, W.*; Matsuda, Tatsuma; Aoki, Dai*; Hardy, F.*; Scheerer, G. W.*; Ballon, G.*; Nardone, M.*; Zitouni, A.*; Meingast, C.*; Flouquet, J.*

We report magnetization and magnetoresistivity measurements on the isostructural ferromagnetic superconductors UCoGe and URhGe in magnetic fields up to 60 T and temperatures from 1.5 to 80 K. At low temperature, a moment polarization in UCoGe in a field H b of around 50T leads to well-defined anomalies in both magnetization and magnetoresistivity. These anomalies vanish in temperatures higher than 30-40 K, where maxima in the magnetic susceptibility and the field-induced variation of the magnetoresistivity are found. A comparison is made between UCoGe and URhGe, where a moment reorientation in a magnetic field H b of 12T leads to field-induced reentrant superconductivity.