Kim You Jin, Konishi Shinya, Okada Mari, Komabuchi Mai, Urushihara Daisuke, Asaka Toru, Tanaka Katsuhisa
Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
Division of Advanced Ceramics, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.
J Phys Condens Matter. 2020 Jul 1;32(40). doi: 10.1088/1361-648X/ab95cd.
TmFeOis one kind of multiferroic material in which equivalent amounts of Feand Feoccupy a two-dimensional triangular lattice, leading to charge and spin frustrations. The spin frustration is expected to be increased as the fraction of Fe(Fe) becomes larger than that of Fe(Fe). We have grown single-crystalline TmFeOwith oxygen vacancies by using floating zone melting method and examined its magnetic properties. On cooling the compound, a long-range magnetic ordering develops around ∼240 K. With further cooling, a maximum of zero-field-cooled (ZFC) magnetization is observed at 186.2 K. The ac magnetic susceptibility obtained by ZFC process also manifests a maximum in its temperature dependence, and the variation of spin-freezing temperature with frequency of ac magnetic field is explainable in terms of the dynamic scaling law with the critical component of 8.68(8). This value suggests that the spin glass transition occurs at 186.2 K. The effect of external dc magnetic field on the irreversible transition temperature is coincident with the de Almeida-Thouless (AT) line. Aging-memory and rejuvenation effect is also observed below the spin-freezing temperature. These facts support the idea that TmFeOundergoes spin glass transition below the ferrimagnetic transition temperature. In other words, TmFeOcan be regarded as a reentrance spin glass. It is thought that the oxygen vacancies bring about unequal number of Feand Feions and thereby strengthen the magnetic frustration among the iron ions coupled with antiferromagnetic interactions, leading to the spin glass behavior.
TmFeO 是一种多铁性材料，其中等量的 Fe³⁺ 和 Fe²⁺ 占据二维三角晶格，导致电荷和自旋受挫。随着 Fe³⁺（Fe²⁺）的比例大于 Fe²⁺（Fe³⁺）的比例，自旋受挫预计会增加。我们使用浮区熔炼法生长了具有氧空位的单晶 TmFeO，并研究了其磁性。在冷却该化合物时，在约 240 K 附近出现长程磁有序。进一步冷却时，在 186.2 K 观察到零场冷却（ZFC）磁化强度的最大值。通过 ZFC 过程获得的交流磁化率在其温度依赖性中也表现出最大值，并且自旋冻结温度随交流磁场频率的变化可以根据具有 8.68(8) 临界分量的动态标度定律来解释。该值表明自旋玻璃转变发生在 186.2 K。外部直流磁场对不可逆转变温度的影响与德阿尔梅达 - 图勒斯（AT）线一致。在自旋冻结温度以下还观察到老化记忆和恢复效应。这些事实支持了 TmFeO 在亚铁磁转变温度以下经历自旋玻璃转变的观点。换句话说，TmFeO 可被视为一种再入自旋玻璃。据认为，氧空位导致 Fe³⁺ 和 Fe²⁺ 离子数量不等，从而增强了与反铁磁相互作用耦合的铁离子之间的磁受挫，导致自旋玻璃行为。
