Abstract
The Jahn–Teller (JT) effect, through geometric deformation of molecules or local ionic lattices, lowers the overall energy of the system by removing electron degeneracy from partially occupied orbitals. Crystal symmetry lowered by JT distortion inevitably creates multiple variants of elastic and orbital-anisotropic states. Visualization and control of the domain/wall textures create a cornerstone to understand various correlated phenomena and explore wall properties. Here, we report the real-space observation of JT phonon and orbiton-related domains in a LaMnO3 thin film using confocal Raman spectromicroscopy. The characteristic symmetries of the JT-originated Raman modes allow us to detect and visualize the local population and orientation of the JT planes. Combined with a crystal structural analysis, we find that the formation of ferroelastic domains with W or W’ walls provides the basic framework for understanding JT domain textures. Furthermore, we demonstrate the JT domains can be manipulated by applying local external stress. Our findings provide a useful pathway for mechanically-tunable orbitronic applications.
Highlights
Transition metal oxides exhibit a plethora of functional properties and quantum phenomena, including high-temperature superconductivity, colossal magnetoresistance, and electrochemical catalytic activity via strong inter-couplings among spin, charge, and lattice degrees of freedom[1,2,3,4,5,6]
Double or superexchange interactions were proposed to account for the interplay of magnetism and transport properties[7,8], and the basic principles strongly rely on the presence of charge ordering[9,10], Jahn–Teller (JT) distortion[11,12,13], and orbital ordering (OO)[14,15,16,17]
The JT distortion involves the partial removal of the d-electron degeneracy of a transition metal cation in a ligand field, resulting in a reduction in lattice symmetry
Summary
Transition metal oxides exhibit a plethora of functional properties and quantum phenomena, including high-temperature superconductivity, colossal magnetoresistance, and electrochemical catalytic activity via strong inter-couplings among spin, charge, and lattice degrees of freedom[1,2,3,4,5,6]. The metal-insulator transition observed in LMO under high pressure is understood based on a phase-separated configuration consisting of spatial regions of JT distorted and undistorted MnO6 octahedra[26,27]. We implement real-space imaging of the cooperative-JT-distortion and OO domains in an epitaxial LMO thin film using polarized Raman spectroscopy. Construction in terms of ferroelasticity and demonstrate the elastic manipulation of the JT domains by applying local external stresses This discovery provides a useful route for orbital engineering of complex oxides
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