Low temperature properties of ZrTr2Zn20 (Tr = transition metal) with a pyrochlore lattice

TMU International Symposium on "New Quantum Phases Emerging from Novel Crystal Structure"

Hasegawa, S.^1 ; Morihiro, K.^2 ; Kase, N.^1 ; Nakano, T.^1 ; Takeda, N.^2

Graduate School of Science and Technology, Niigata University, Niigata

950-2102, Japan^1

Department of Materials Science and Technology, Niigata University, Niigata

950-2102, Japan^2

关键词: Curie-Weiss behaviors;    Ferromagnetic correlations;    Geometrical frustrations;    Local magnetic moments;    Metallic behaviors;    Pyrochlore lattices;    Residual resistivity ratios;    Sommerfeld coefficient;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/683/1/012021/pdf
DOI  :  10.1088/1742-6596/683/1/012021

来源: IOP

【 摘 要 】

Single crystals of ZrTr2Zn20(Tr = Mn, Co, Ru) with a cubic CeCr2Al20-type structure (space group Fd-3m) were grown by a Zn-flux method. Electrical resistivity ρ(T) of ZrTr2Zn20shows typical metallic behavior with the residual resistivity ratio (RRR) of 1.1 (Mn), 8.4 (Co) and 10 (Ru). Magnetic susceptibility χ(T) of ZrRu2Zn20shows large diamagnetism. χ(T) of ZrTr2Zn20(Tr = Mn, Co) clearly shows Curie-Weiss behavior, indicating that Mn/Co spins are really active as local magnetic moments or that a large spin fluctuation exists. χ(T) of ZrMn2Zn20increases ferromagnetically at around 20 K. Because the anti-ferromagnetic correlation with active localized spins exists in ZrCo2Zn20, geometrical frustration of the pyrochlore lattice of Co is expected. However, specific heat C(T) of ZrCo2Zn20shows no upturn at low temperatures and Sommerfeld coefficient γ is evaluated to be 24.8 mJ/(mol K2). We consider that the localized Co spins are insufficient to cause anomaly originated from the geometrical frustration, or the Co spins exist in a disordered arrangement of excess Co.