Singh Karan, Mukherjee K
School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, 175005, Himachal Pradesh, India.
Sci Rep. 2019 Mar 26;9(1):5131. doi: 10.1038/s41598-019-41565-8.
Polycrystalline CeGe is investigated by means of DC and AC susceptibility, non-linear DC susceptibility, electrical transport and heat capacity measurements in the low temperature regime. This compound shows two peaks at low magnetic field around T ~ 10.7 and T ~ 7.3 K due to antiferromagnetic ordering and subsequent spin rearrangement respectively. Investigation of non-linear DC susceptibility reveals a presence of higher order magnetization which results in the development of a new order parameter around T. This leads to a lowering of symmetry of the magnetic state. The order parameter increases with decreasing temperature and stabilizes around T. Consequently, the symmetry of the magnetic state is preserved below this transition. Heat capacity and resistivity results indicate the presence of a gap opening around T on portion of Fermi surface, due to evolution of the Fermi surface. Magnetoresistance behavior and violation of Kohler's rule suggest that the evolution of Fermi surface changes the symmetry of magnetic state. The observation of new order parameter (which is of second order) is also confirmed from the Landau free energy theory.
通过在低温区域进行直流和交流磁化率、非线性直流磁化率、电输运和热容量测量，对多晶CeGe进行了研究。该化合物在低磁场下分别在T ~ 10.7 K和T ~ 7.3 K附近出现两个峰，分别归因于反铁磁有序和随后的自旋重排。非线性直流磁化率的研究揭示了高阶磁化的存在，这导致在T附近出现一个新的序参量。这导致磁态对称性降低。序参量随温度降低而增加，并在T附近稳定下来。因此，磁态对称性在该转变以下得以保留。热容量和电阻率结果表明，由于费米面的演化，在T附近费米面的一部分出现能隙打开。磁阻行为和对科勒规则的违反表明，费米面的演化改变了磁态对称性。从朗道自由能理论也证实了新序参量（二阶）的观测结果。
