Abstract
We report the static and dynamic magnetic properties of LaSrCrO4, a seemingly canonical spin-3/2 square-lattice antiferromagnet that exhibits frustration between magnetic layers - owing to their AB stacking - and offers a rare testbed to investigate accidental-degeneracy lifting in magnetism. Neutron diffraction experiments on single-crystal samples uncover a remarkable anticollinear magnetic order below TN = 170 K characterized by a Néel arrangement of the spins within each layer and an orthogonal arrangement between adjacent layers. To understand the origin of this unusual magnetic structure, we analyze the spin-wave excitation spectrum by means of inelastic neutron scattering and bulk measurements. A spectral gap of 0.5 meV, along with a spin-flop transition at 3.2 T, reflect the energy scale associated with the degeneracy-lifting. A minimal model to explain these observations requires both a positive biquadratic interlayer exchange and dipolar interactions, both of which are on the order of 10-4 meV, only a few parts per million of the dominant exchange interaction J1≈11 meV. These results provide direct evidence for the selection of a noncollinear magnetic structure by the combined effect of two distinct degeneracy lifting interactions.
Original language | English |
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Article number | L180411 |
Journal | Physical Review B |
Volume | 105 |
Issue number | 18 |
DOIs | |
State | Published - May 1 2022 |
Funding
We thank Cristian Batista and Hitesh Changlani for helpful discussions. This research used resources at the High Flux Isotope Reactor and Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The work at Institute of Physics was supported by the National Natural Science Foundation of China (Grants No. 11974396, No. 12025408, No. 11874400, and No. 12188101), the Ministry of Science and Technology (2018YFA0305700), and the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB33020300). The work of Q.H. and H.Z. at the University of Tennessee was supported by the National Science Foundation under Award No. DMR-2003117. The work of Z.L.D., X.B., and M.M. at Georgia Tech (neutron-scattering experiment and data analysis) was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division under Award No. DE-SC-0018660.