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Neutron Scattering Study of Magnetic Anisotropy in the Tetragonal Antiferromagnet Bi2CuO4



Bo Yuan, Nicholas Butch, Guangyong Xu, Barry Winn, J. P. Clancy, Young-June Kim


We report neutron scattering study of low energy magnetic excitations in S =1/2 quantum magnet Bi2CuO4 with a tetragonal lattice structure. Our observation of a spin flop transition at a small field of 0.4 Tesla indicates the existence of a small anisotropy within the easy plane. Since any magnetic anisotropy is forbidden by symmetry within the easy-plane on a classical level and the simple lattice structure of Bi2CuO4 rules out any other types of in-plane anisotropy found in other cuprates, the observed anisotropy is attributed to a pure quantum effect. Our calculation of magnon quantum zero point fluctuation shows this quantitatively. The model spin Hamiltonian used for the calculation, incorporation Dzyaloshinskii-Moriya and symmetric anisotropic interactions, is determined independently from the experimental dispersion of the out-of-plane mode. Our results clearly demonstrates that Bi2CuO4 is a textbook example of anisotropy generated by quantum fluctuation.
Physical Review B


quantum magnet, spin fluctuation, inelastic neutron scattering


Yuan, B. , Butch, N. , Xu, G. , Winn, B. , Clancy, J. and Kim, Y. (2021), Neutron Scattering Study of Magnetic Anisotropy in the Tetragonal Antiferromagnet Bi<sub>2</sub>CuO<sub>4</sub>, Physical Review B (Accessed June 18, 2024)


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Created April 25, 2021, Updated October 1, 2021