Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, India.
J Phys Condens Matter. 2013 Oct 30;25(43):435603. doi: 10.1088/0953-8984/25/43/435603. Epub 2013 Oct 4.
The anisotropic magnetic properties of the antiferromagnetic compound CePd2Ge2, crystallizing in the tetragonal crystal structure have been investigated in detail on a single crystal grown by the Czochralski method. From the electrical transport, magnetization and heat capacity data, the Néel temperature is confirmed to be 5.1 K. Anisotropic behaviour of the magnetization and resistivity is observed along the two principal crystallographic directions-namely, [100] and [001]. The isothermal magnetization measured in the magnetically ordered state at 2 K exhibits a spin reorientation at 13.5 T for the field applied along the [100] direction, whereas the magnetization is linear along the [001] direction attaining a value of 0.94 μ(B)/Ce at 14 T. The reduced value of the magnetization is attributed to the crystalline electric field (CEF) effects. A sharp jump in the specific heat at the magnetic ordering temperature is observed. After subtracting the phononic contribution, the jump in the heat capacity amounts to 12.5 J K(-1)mol(-1) which is the expected value for a spin ½ system. From the CEF analysis of the magnetization data the excited crystal field split energy levels were estimated to be at 120 K and 230 K respectively, which quantitatively explains the observed Schottky anomaly in the heat capacity. A magnetic phase diagram has been constructed based on the field dependence of magnetic susceptibility and the heat capacity data.
我们详细研究了在提拉法生长的单晶上的反铁磁化合物 CePd2Ge2 的各向异性磁性质，该化合物具有四方晶体结构。从电输运、磁化和热容数据可以确定尼尔温度为 5.1 K。在磁有序状态下，在 2 K 下测量的各向异性磁化和电阻率在两个主要晶向——即[100]和[001]上表现出各向异性。在沿[100]方向施加的磁场下，在 13.5 T 时观察到自旋重定向，而在[001]方向上磁化是线性的，在 14 T 时达到 0.94 μ(B)/Ce 的值。磁化的降低归因于晶场（CEF）效应。在磁有序温度处观察到比热的急剧跳跃。扣除声子贡献后，热容的跃变量为 12.5 J K(-1)mol(-1)，这是自旋½系统的预期值。从磁化数据的 CEF 分析中，估计了激发的晶场分裂能级分别为 120 K 和 230 K，这定量解释了热容中的肖特基异常。根据磁化率和热容数据的磁场依赖性，构建了一个磁相图。
