Wang Shanmin, Chen Jian, Wu Liusuo, Zhao Yusheng
Department of Physics and Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China.
Phys Rev Lett. 2022 Mar 4;128(9):095702. doi: 10.1103/PhysRevLett.128.095702.
Coupling of charge and lattice degrees of freedom in materials can produce intriguing electronic phenomena, such as conventional superconductivity where the electrons are mediated by lattice for creating supercurrent. The Mott transition, which is a source for many fascinating emergent behaviors, is originally thought to be driven solely by correlated electrons with an Ising criticality. Recent studies on the known Mott systems have shown that the lattice degree of freedom is also at play, giving rise to either Landau or unconventional criticality. However, the underlying coupling mechanism of charge and lattice degrees of freedom around the Mott critical end point remains elusive, leading to difficulties in understanding the associated Mott physics. Here, we report a study of Mott transition in cubic PbCrO_{3} by measuring the lattice parameter, using high-pressure x-ray diffraction techniques. The Mott criticality in this material is revealed with large lattice anomalies, which is governed by giant viscoelasticity that presumably results from a combination of lattice elasticity and electron viscosity. Because of the viscoelastic effect, the lattice of this material behaves peculiarly near the critical end point, inconsistent with any existing university classes. We argue that the viscoelasticity may play as a hidden degree of freedom behind the Mott criticality.
材料中电荷与晶格自由度的耦合能够产生有趣的电子现象，比如传统超导现象，其中电子通过晶格介导来产生超电流。莫特转变是许多迷人的涌现行为的根源，最初被认为仅由具有伊辛临界性的关联电子驱动。近期对已知莫特体系的研究表明，晶格自由度也起着作用，会导致朗道临界性或非常规临界性。然而，在莫特临界端点附近，电荷与晶格自由度的潜在耦合机制仍然难以捉摸，这给理解相关的莫特物理带来了困难。在此，我们通过使用高压X射线衍射技术测量晶格参数，报告了对立方PbCrO₃中莫特转变的一项研究。该材料中的莫特临界性通过大的晶格异常得以揭示，这种异常由巨大的粘弹性控制，推测这是晶格弹性和电子粘性共同作用的结果。由于粘弹性效应，该材料的晶格在临界端点附近表现奇特，与任何现有的普遍类别都不一致。我们认为，粘弹性可能是莫特临界性背后一个隐藏的自由度。
