Reentrant spin glass state induced by structural phase transition in La0.4Ce0.6Co2P2
Reentrant spin glass state induced by structural phase transition in La0.4Ce0.6Co2P2
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DOI：
10.1103/physrevmaterials.4.074412
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发表时间：
2020-07-22
影响因子：
3.4
通讯作者：
Shatruk, Michael
中科院分区：
文献类型：
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作者：
Clark, Judith K.;Tan, Xiaoyan;Shatruk, Michael
La0.4Ce0.6Co2P2是伪二元体系LaCo2P2-CeCo2P2中形成固溶体的一个临界情况。材料在225k时发生铁磁有序，在190k时发生结构坍塌，导致磁化强度的强烈抑制。结构相变表现为四边形晶格参数c的逐渐减小和参数a的相对较小的增加。有趣的是，磁性测量和非极化和极化中子散射实验的结合表明，结构坍塌不会导致反铁磁有序态，这在Ce含量较高的样品中观察到。相反，La0.4Ce0.6Co2P2似乎进入了无序的自旋玻璃态，铁磁有序的逐渐耗散与结构坍塌同时发生，这可以通过对穿过样品的极化中子束的退极化因子的温度依赖测量来证明。观察到的行为类似于报道的所谓可重入自旋玻璃。然而，在目前的情况下，可重入自旋玻璃的出现不是由调整化学成分引起的，而是由结构相变引起的。电子结构计算证实，磁有序的损失是由于材料晶体结构的变化引起的费米能级态密度的细微变化引起的。
La0.4Ce0.6Co2P2 represents a borderline case in the range of solid solutions formed in the pseudobinary system LaCo2P2-CeCo2P2. The material undergoes ferromagnetic ordering at similar to 225 K followed by a structural collapse at similar to 190 K, which leads to a strong suppression of magnetization. The structural phase transition manifests itself in a gradual decrease in the parameter c and a relatively smaller increase of the parameter a of the tetragonal lattice. Interestingly, a combination of magnetic measurements and nonpolarized and polarized neutron scattering experiments suggests that the structural collapse does not lead to an antiferromagnetically ordered state, observed in samples with the higher Ce content. On the contrary, La0.4Ce0.6Co2P2 appears to enter a disordered, spin glass state, with gradual dissipation of the ferromagnetic ordering taking place simultaneously with the structural collapse, as evidenced by temperature-dependent measurements of the depolarization factor for a polarized neutron beam passing through the sample. The observed behavior is analogous to that reported for so-called reentrant spin glasses. In the present case, however, the appearance of the reentrant spin glass regime is caused not by tuning the chemical composition but by the structural phase transition. Electronic structure calculations confirm that the loss of magnetic ordering is caused by the subtle change to the density of states at the Fermi level due to the variation of the crystal structure of the material.