Pranab Kumar Das, K. Ramesh Kumar, R. Kulkarni, S. K. Dhar, A. Thamizhavel
The equiatomic PrGe single crystal was grown by Czochralski pulling method. The grown single crystal was found to have CrB-type orthorhombic crystal structure with the space group \textit{Cmcm} (#63). Transport and magnetization data reveal large anisotropy in the electrical resistivity, magnetic susceptibility and magnetization. PrGe was found to exhibit two consecutive magnetic orderings at 44 K and 41.5 K, respectively. The magnetic susceptibility measurement along the three principal directions, in low applied fields, revealed a cusp like behaviour at 44 K while at 41.5 K a ferromagnetic like increase was observed. The hysteritic behaviour in the magnetization measurement at 1.8 K confirmed the ferromagnetic nature of PrGe at low temperatures. The heat capacity data clearly revealed the bulk nature of two magnetic transitions by the presence of two sharp peaks attaining values exceeding 40 J/K$\cdot$mol at the respective temperatures. The entropy reached $\mathtt{R}$ ln(4) immediately above the magnetic ordering indicating the low lying crystal field split levels in this compound. The low temperature data of electrical resistivity and the magnetic part of heat capacity show an existence of gap in the spin-wave spectrum.
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http://arxiv.org/abs/1207.3935
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