论文标题
van vleck激子在ca $ _ {2} $ ruo $ _ {4} $中
Van Vleck excitons in Ca$_{2}$RuO$_{4}$
论文作者
论文摘要
提出了一个框架，用于建模和理解局部，中间耦合磁体中的磁激发，其中已知自旋轨道耦合，磁交换和晶体场效应之间的相互作用会产生非常规磁性行为和基础状态的复杂景观。一种用于建模这些激发的自旋轨道激子方法是根据哈密顿量明确结合单离子晶体电场和自旋交换项开发的。然后将该框架利用以理解一个规范的VAN VLECK $ J \ rm {_ {eff}} = 0 $ singlet接地状态，其激发是耦合的旋转和结晶电场水平。具体而言，异常的希格斯模式[Jain等。纳特。物理。 13，633（2017）]，自旋波[S. Kunkemöller等人。物理。莱特牧师。 115，247201（2015）]和轨道激发[L. Das等。物理。 Rev. X 8，011048（2018）]在多纤维Mott绝缘子CA $ _2 $ ruo $ _4 $中被捕获，并与以前的中子和无弹性X射线光谱测量找到了良好的协议。此外，我们的结果说明了结晶电场诱导的单线基态如何支持相干纵向或振幅激发以及横向波动型动力学。我们使用此描述来讨论访问附近关键点的机制。
A framework is presented for modeling and understanding magnetic excitations in localized, intermediate coupling magnets where the interplay between spin-orbit coupling, magnetic exchange, and crystal field effects are known to create a complex landscape of unconventional magnetic behaviors and ground states. A spin-orbit exciton approach for modeling these excitations is developed based upon a Hamiltonian which explicitly incorporates single-ion crystalline electric field and spin exchange terms. This framework is then leveraged to understand a canonical Van Vleck $j\rm{_{eff}}=0$ singlet ground state whose excitations are coupled spin and crystalline electric field levels. Specifically, the anomalous Higgs mode [Jain et al. Nat. Phys. 13, 633 (2017)], spin-waves [S. Kunkemöller et al. Phys. Rev. Lett. 115, 247201 (2015)], and orbital excitations [L. Das et al. Phys. Rev. X 8, 011048 (2018)] in the multiorbital Mott insulator Ca$_2$RuO$_4$ are captured and good agreement is found with previous neutron and inelastic x-ray spectroscopic measurements. Furthermore, our results illustrate how a crystalline electric field-induced singlet ground state can support coherent longitudinal, or amplitude excitations, and transverse wavelike dynamics. We use this description to discuss mechanisms for accessing a nearby critical point.
