Pulsed high magnetic field measurements in a quasi-degenerate diluted Yb system (Lu,Yb)RhZn

Kitazawa, Takafumi  ; Ikeda, Yoichi*; Matsuo, Akira*; Imajo, Shusaku*; Shimizu, Yusei*; Kawamata, Masahiro*; Tokunaga, Yo  ; Haga, Yoshinori   ; Opletal, P.  ; Sakai, Hironori   ; Tokiwa, Yoshifumi  ; Yamamoto, Etsuji  ; Kambe, Shinsaku  ; Kohama, Yoshimitsu*; Kindo, Koichi*; Fujita, Masaki*

A diluted Yb system (Lu,Yb)RhZn is an impurity Kondo alloy with quasi-octet degeneracy due to strong - hybridization. In addition to the large degeneracy of , we found field-induced single-ion magnetic anisotropy above about 5 T, which cannot be explained by the existing Kondo model. To understand the -electron state under magnetic fields, where the magnetic anisotropy develops, we measured the magnetization and specific heat of the diluted Yb system (Lu,Yb)RhZn under pulsed high magnetic fields. The magnetization curves coincided between the processes of increasing and decreasing magnetic fields. This indicates that eddy-current heating is sufficiently suppressed, and isothermal magnetization curves can be measured. The magnetic easy and hard axes along the and directions, respectively, remained unchanged even above the Kondo crossover field of 22.7 T, where the -electrons are localized. The field dependence of the electronic specific heat coefficients, estimated from the specific heat measurements, increased to about 1 J Yb-mol K and decreased around the Kondo crossover field. The decreasing electronic specific heat coefficients at the Kondo field suggest the localization of the -electrons. In addition, the anisotropic magnetic response was observed not only in magnetization but also in specific heat measurements.