Fernández-Ruiz Toraya, Sánchez-Movellán Inés, García-Lastra Juan María, Moreno Miguel, Aramburu José Antonio, García-Fernández Pablo
Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria, Cantabria Campus Internacional, Avenida de los Castros s/n, 39005 Santander, Spain.
Department of Energy Conversion and Storage, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
J Phys Chem Lett. 2024 Jun 27;15(25):6476-6481. doi: 10.1021/acs.jpclett.4c01256. Epub 2024 Jun 13.
Spatial degeneracy is the cause of the complex electronic, geometrical, and magnetic structures found in a number of materials whose more representative example is KCuF. In the literature the properties of this lattice are usually explained through the Kugel--Khomskii model, based on superexchange interactions. Here we provide rigorous theoretical and computational arguments against this view proving that structural and magnetic properties essentially arise from electron-vibration (vibronic) interactions. Moreover, based on the work of Öpik and Pryce, we show that the coupling between lattice (homogeneous strain) and motif (phonons) distortions is essential to understand the main stable configurations of the lattice. Using this information, we predict a new low-energy phase in KCuF that could strongly alter its properties and provide guidance on how to stabilize it through strain engineering.
空间简并是在许多材料中发现的复杂电子、几何和磁结构的原因，其中更具代表性的例子是KCuF。在文献中，这种晶格的性质通常通过基于超交换相互作用的库格尔 - 霍姆斯基模型来解释。在这里，我们提供了反对这种观点的严格理论和计算论据，证明结构和磁性质本质上源于电子 - 振动（电子 - 声子）相互作用。此外，基于奥皮克和普赖斯的工作，我们表明晶格（均匀应变）和基序（声子）畸变之间的耦合对于理解晶格的主要稳定构型至关重要。利用这些信息，我们预测KCuF中一种新的低能相，它可能会强烈改变其性质，并为如何通过应变工程使其稳定提供指导。
