Electronic structure of the frustrated diamond lattice magnet NiRh2O4
Electronic structure of the frustrated diamond lattice magnet NiRh2O4
复制标题
DOI：
10.1103/physrevb.106.045134
复制
发表时间：
2022-07
影响因子：
3.7
通讯作者：
B. Zager;J. Chamorro;L. Ge;F. Bahrami;V. Bisogni;J. Pelliciari;J. Li;G. Fabbris;T. McQueen;M. Mourigal;K. Plumb
中科院分区：
文献类型：
--
作者：
B. Zager;J. Chamorro;L. Ge;F. Bahrami;V. Bisogni;J. Pelliciari;J. Li;G. Fabbris;T. McQueen;M. Mourigal;K. Plumb
尖晶石是目前已知的唯一一种自旋为1的金刚石晶格磁体，并被预测会产生由受挫的近邻交换和次近邻交换以及轨道简并驱动的非常规磁现象。以前的工作没有发现磁有序的迹象，但发现了一个间隙色散磁激发，表明可能存在价键磁基态。然而，许多相互竞争的低能量自由度和有限的经验微观约束的存在使进一步的分析复杂化。本文采用共振非弹性x射线散射（RIXS）、x射线吸收光谱（XAS）和非弹性中子散射（INS）来表征材料的局部电子结构和晶格动力学。RIXS的数据可以部分地用四面体协调的单离子模型来描述，并表明一个四面体扭曲将轨道分裂成高能轨道单重态和低能量轨道双重态。我们发现RIXS光谱的特征与Rh-Ni两位点激发一致，表明氧介导的强金属-金属杂化。我们还通过声子边带的出现来识别电子-声子耦合的特征，这些边带可以修饰晶体场激发。这些结果建立了与磁性相关的关键能量尺度，并进一步证明了共价和晶格动力学在控制原位尖晶石的磁性基态中起着重要作用。
The-site spinelis the only known realization of a spin-1 diamond lattice magnet and is predicted to host unconventional magnetic phenomena driven by frustrated nearest and next-nearest neighbor exchange as well as orbital degeneracy. Previous works found no sign of magnetic order but found a gapped dispersive magnetic excitation indicating a possible valence bond magnetic ground state. However, the presence of many competing low energy degrees of freedom and limited empirical microscopic constraints complicates further analysis. Here we carry out resonant inelastic x-ray scattering (RIXS), x-ray absorption spectroscopy (XAS), and inelastic neutron scattering (INS) to characterize the local electronic structure and lattice dynamics of. The RIXS data can be partly described by a single-ion model for tetrahedrally coordinatedand indicates a tetragonal distortionmeV that splits theorbitals into a high energy orbital singlet and lower energy orbital doublet. We identify features of the RIXS spectra that are consistent with a Rh-Ni two-site excitation indicating strong metal-metal hybridization mediated by oxygen in. We also identify signatures of electron-phonon coupling through the appearance of phonon sidebands that dress crystal field excitations. These results establish the key energy scales relevant to the magnetism inand further demonstrate that covalency and lattice dynamics play essential roles in controlling the magnetic ground states of-site spinels.