Anticollinear order and degeneracy lifting in square lattice antiferromagnet LaSrCrO4

Abstract

We report the static and dynamic magnetic properties of LaSrCrO${}_4$, 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 $T_N$ = 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 $J_1\approx 11$ meV. These results provide direct evidence for the selection of a non-collinear magnetic structure by the combined effect of two distinct degeneracy lifting interactions.

arXiv comment6 pages of main tex with 16 pages of supplemental material

References in corpus (26)

• Spin-lattice coupling in frustrated antiferromagnets
• Dipolar Interactions and Origin of Spin Ice in Ising Pyrochlore Magnets
• Long Range Order at Low Temperature in Dipolar Spin Ice
• Order by distortion and string modes in pyrochlore antiferromagnet
• Neel Temperature of Quasi-Low-Dimensional Heisenberg Antiferromagnets
• Fractional excitations in the square-lattice quantum antiferromagnet
• Magnetic multipole analysis of kagome and artificial ice dipolar arrays
• Definitive Evidence for Order-by-Quantum-Disorder in Er2Ti2O7
• Two-stage ordering of spins in a dipolar spin ice on the kagome lattice
• Anomalous High-Energy Spin Excitations in La2CuO4
• Spin-Peierls phases in pyrochlore antiferromagnets
• Systematic derivation of realistic spin-models for beyond-Heisenberg solids
• Removing the spin ice cap: magnetic ground states of rare earth tripod kagome lattice Mg${}_2$RE${}_3$Sb${}_3$O${}_{14}$ (RE = Gd, Dy, Er)
• Emergent Order in the Kagome Ising Magnet Dy3Mg2Sb3O14
• Experimental Insights into Ground State Selection of Quantum XY Pyrochlores
• Finite Temperature Transitions in Large Magnetic Field in Dipolar Spin Ice
• Order by Disorder Spin Wave Gap in the XY Pyrochlore Magnet Er2Ti2O7
• Order by quenched disorder in the model triangular antiferromagnet RbFe(MoO4)2
• Magnetic spectrum of the two-dimensional antiferromagnet La2CoO4 studied by inelastic neutron scattering
• Quantum versus Classical Spin Fragmentation in Dipolar Kagome Ice Ho3Mg2Sb3O14
• Spin-Charge Coupling in lightly doped Nd${}_{2-x}$Ce${}_x$CuO${}_4$
• Magnetic structure and magnon dispersion in LaSrFeO${}_4$
• Magnetic susceptibility anisotropies in a two-dimensional quantum Heisenberg antiferromagnet with Dzyaloshinskii-Moriya interactions
• Melting of magnetic correlations in charge-orbital ordered La(0.5)Sr(1.5)MnO(4) : competition of ferro and antiferromagnetic states
• Control of effective free energy landscape in a frustrated magnet by a field pulse
• Nonequilibrium selection of magnetic order in driven triangular XY antiferromagnet

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