A structural distortion induced magneto-elastic locking in Sr${}_2$IrO${}_4$ revealed through nonlinear optical harmonic generation

Abstract

We report a global structural distortion in Sr${}_2$IrO${}_4$ using spatially resolved optical second and third harmonic generation rotational anisotropy measurements. A symmetry lowering from an $I{4}_1/acd$ to $I{4}_1/a$ space group is observed both above and below the Néel temperature that arises from a staggered tetragonal distortion of the oxygen octahedra. By studying an effective super-exchange Hamiltonian that accounts for this lowered symmetry, we find that perfect locking between the octahedral rotation and magnetic moment canting angles can persist even in the presence of large non-cubic local distortions. Our results explain the origin of the forbidden Bragg peaks recently observed in neutron diffraction experiments and reconcile the observations of strong tetragonal distortion and perfect magneto-elastic locking in Sr${}_2$IrO${}_4$.

6 pages, 4 figures

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Cited by in corpus (11)

• Observation of a ferro-rotational order coupled with second-order nonlinear optical fields
• Square Lattice Iridates
• Electrical Control of Structural and Physical Properties via Strong Spin-Orbit Interactions in Sr2IrO4
• Strong Pseudospin-Lattice Coupling in Sr3Ir2O7: Coherent Phonon Anomaly and Negative Thermal Expansion
• First-Principles Calculation of Spin and Orbital Contributions to Magnetically Ordered Moments in Sr${}_2$IrO${}_4$
• Spin-orbit-enhanced magnetic surface second-harmonic generation in Sr${}_2$IrO${}_4$
• Structural evolution and electronic properties of (Sr1-xCax)2-yIrO4+z spin-orbit assisted insulators
• Towards Electrical-Current Control of Quantum States in Spin-Orbit-Coupled Matter
• Nonsymmorphic Dirac semimetal and carrier dynamics in doped spin-orbit-coupled Mott insulator Sr${}_2$IrO${}_4$
• Doping driven structural distortion in the bilayer iridate (Sr${}_{1-x}$La${}_x$)${}_3$Ir${}_2$O${}_7$
• Fortuitous partners of antiferromagnetic and Mott states in spin-orbit-coupled Sr2IrO4: A study of Sr2Ir1-xMxO4 (M=Fe or Co)