Jin Lun, Peng Shiyu, Rutherford Aya Nakano, Xu Xianghan, Ni Danrui, Yang Chen, Byeon Yen Ji, Xie Weiwei, Zhou Haidong, Dai Xi, Cava Robert J
Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China.
Sci Adv. 2024 Oct 11;10(41):eadp4685. doi: 10.1126/sciadv.adp4685.
Pyroxenes (AMXO) consisting of infinite one-dimensional edge-sharing MO chains and bridging XO tetrahedra are fertile ground for finding quantum materials. Thus, here, we have studied calcium cobalt germanate (CaCoGeO) and calcium cobalt silicate (CaCoSiO) crystals in depth. Heat capacity data show that the spins in both compounds are dominantly Ising-like, even after being manipulated by high magnetic fields. On cooling below the Néel temperatures, a sharp field-induced transition in magnetization is observed for CaCoGeO, while multiple magnetization plateaus beneath the full saturation moment are spotted for CaCoSiO. Our analysis shows that these contrasting behaviors potentially arise from the different electron configurations of germanium and silicon, in which the 3d orbitals are filled in the former but empty in the latter, enabling electron hopping. Thus, silicate tetrahedra can aid the interchain superexchange pathway between cobalt(II) ion centers, while germanate ones tend to block it during magnetization.
由无限一维边缘共享MO链和桥连XO四面体组成的辉石（AMXO）是寻找量子材料的沃土。因此，在此我们深入研究了锗酸钙钴（CaCoGeO）和硅酸钙钴（CaCoSiO）晶体。热容数据表明，即使在高磁场作用下，这两种化合物中的自旋主要呈类伊辛型。在冷却至奈尔温度以下时，观察到CaCoGeO的磁化强度出现明显的场致转变，而CaCoSiO则在完全饱和磁矩以下出现多个磁化平台。我们的分析表明，这些不同的行为可能源于锗和硅不同的电子构型，其中前者的3d轨道被填满，而后者为空，从而使得电子能够跳跃。因此，硅酸盐四面体有助于钴（II）离子中心之间的链间超交换途径，而锗酸盐四面体在磁化过程中倾向于阻碍它。
