Isotropic \Gamma_6 Ground State in Caged Compound NdRu2Zn20

• Published in: arXiv.org
• Main Authors: Isikawa, Yosikazu, Ejiri, Jun-ichi, Mizushima, Toshio, Kuwai, Tomohiko
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 07.10.2013
• Subjects: Axes (reference lines); Cage compounds; Crystallography; Curie temperature; Electric fields; Ferromagnetic phases; Ferromagnetism; Ground state; Heat exchange; Magnetic anisotropy; Magnetic fields; Magnetic permeability; Magnetism; Magnetization; Magnetization curves; Phase transitions; Physics - Strongly Correlated Electrons; Temperature dependence
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1310.1664

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 \(T_{\rm C}=1.9\) K in both the temperature dependence of \(\chi(T)\) and \(C(T)\). Below \(T_{\rm C}\), 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 \(T_{\rm C}\). 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.