Abstract
We report the evolution of the charge density wave (CDW) states in the quasi-two-dimensional rare-earth tritellurides ( for , Tm) under the influence of in-plane uniaxial stress. Measurements of the elastocaloric effect, resistivity, and elastoresistivity allow us to demonstrate the importance of in-plane antisymmetric strain on the CDW and to establish a phase diagram. We show that modest tensile stress parallel to the in-plane axis can reversibly switch the direction of the ordering wave vector between the two in-plane directions, and present a free-energy expansion which reproduces the general structure of the observed phenomena. This work opens a new avenue in the study of in its own right, and more generally establishes as a promising model system for the study of strain-CDW interactions in a quasi-two-dimensional square lattice.
- Received 7 January 2022
- Revised 13 March 2022
- Accepted 15 April 2022
DOI:https://doi.org/10.1103/PhysRevX.12.021046
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
In conventional metals, conduction electrons usually adopt a spatially uniform distribution. In strongly correlated metals, the conduction electrons sometimes organize into spatial patterns with a preferred direction, known as unidirectional charge-ordered states. However, strong correlations also give rise to other forms of order (such as magnetism), and it can be difficult to disentangle the effects of one phase from another.
In this study, we focus on a material where charge order can be studied in isolation. We investigate the response of a charge-ordered state in the quasi-2D rare-earth tritellurides (, where is any rare-earth element), where the electronic properties arise from nearly square nets of tellurium atoms residing within a weakly orthorhombic crystal structure.
In our measurements, we focus on the elastocaloric effect and elastoresistivity, defined as strain derivatives of the entropy and normalized resistivity, respectively. With the resulting thermodynamic and transport evidence, we identify a heretofore unobserved strain-induced transition in which the wave vector of the charge-ordered state rotates by 90° to align with tensile strain. Importantly, we show that this occurs at modest strain magnitudes, which are easily achievable in the laboratory.
This work establishes as a tractable model system for the study of the interaction between unidirectional charge order and symmetry-breaking strains within the context of a square crystal lattice. Measurements in under strain might provide some insights that also apply to charge order in strongly correlated systems with similar square-lattice structures, such as the cuprates and heavy-fermion superconductors.
