论文标题
镁级超级相变
Magnonic Superradiant Phase Transition
论文作者
论文摘要
我们表明，在〜4 K的临界温度下发生的ERFEO3中的低温相变，可以描述为超级相变（SRPT）的宏伟版本。光子在量子 - 光学SRPT中的作用是由Fe镁扮演的，而两级原子的作用是由ER旋转弹奏的。我们的自旋模型还原为扩展的DICKE模型，还考虑了ER旋转之间的短距离交换相互作用，除了由FE镁介导的远距离ER-ER相互作用。通过使用由最近的Terahertz磁光谱和磁化实验确定的现实参数，我们证明了导致相变的ER旋转和Fe镁之间的合作，超肌耦合。因此，这项工作证明ERFEO3是一个独特的系统，与先前对激光驱动的非平衡SRPT的观察结果相比，在热平衡中表现出SRPT。
We show that the low-temperature phase transition in ErFeO3 that occurs at a critical temperature of ~ 4 K can be described as a magnonic version of the superradiant phase transition (SRPT). The role of photons in the quantum-optical SRPT is played by Fe magnons, while that of two-level atoms is played by Er spins. Our spin model, which is reduced to an extended Dicke model, takes into account the short-range, direct exchange interactions between Er spins in addition to the long-range Er-Er interactions mediated by Fe magnons. By using realistic parameters determined by recent terahertz magnetospectroscopy and magnetization experiments, we demonstrate that it is the cooperative, ultrastrong coupling between Er spins and Fe magnons that causes the phase transition. This work thus proves ErFeO3 to be a unique system that exhibits a SRPT in thermal equilibrium, in contrast to previous observations of laser-driven non-equilibrium SRPTs.
