Isotropic Γ_6 Ground State in Caged Compound NdRu2Zn20

Abstract

The magnetic susceptibility $\chi$, the magnetization $M$, and the specific heat $C$ were measured for the caged cubic compound NdRu${}_2$Zn${}_{20}$ at temperatures down to 0.5 K in the magnetic field $H$ along the three crystallographic principal axes, [100], [110], and [111]. The ferromagnetic phase transition was observed at the Curie temperature $T_{\mathrm{C}}=1.9$ K in both the temperature dependence of $\chi (T)$ and $C(T)$. Below $T_{\mathrm{C}}$, the magnetization curves $M(H)$ show very weak magnetic anisotropy, and the $C(T)$ curves in the fields along the three principal axes show no magnetic anisotropy both below and above $T_{\mathrm{C}}$. The easy direction of magnetization at 0.5 K changes from the [111] direction in 0 T to the [110] diretion in 7 T. We analyzed these characteristic behaviors theoretically taking into account the crystalline-electric-field energy, the magnetic exchange interaction, and the Zeeman energy. It was found that these features are originated from the isotropic ${\Gamma }_6$ ground state mixing with the magnetic ${\Gamma }_8^{(1)}$ excited state. The temperature and the magnetic field dependences of $M(T,H)$ and $C(T,H)$ are quantitatively well analyzed by this theoretical calculation.

5 pages, 6 figures

References in corpus (3)

• YSix closely related YbT${}_2$Zn${}_{20}$ (T = Fe, Co, Ru, Rh, Os, Ir) heavy fermion compounds with large local moment degeneracy
• Simultaneous Superconducting and Antiferroquadrupolar Transitions in PrRh${}_2$Zn${}_{20}$
• Enhancement of Curie temperature due to the coupling between Fe itinerant electrons and Dy localized electrons in DyFe2Zn20

Cited by in corpus (2)

• Magnetic and Thermal Properties of SmRh${}_2$Zn${}_{20}$ Single Crystal
• Inelastic neutron scattering study of crystalline electric field excitations in the caged compounds NdT2Zn20 (T = Co, Rh, and Ir)