Dzyaloshinsky-Moriya antisymmetric exchange coupling in cuprates: Oxygen effects
- Ural State University (Russian Federation), E-mail: alexandr.moskvin@usu.ru
We reconsider the conventional Moriya approach to the Dzyaloshinsky-Moriya antisymmetric exchange coupling for a single Cu{sub 1}-O-Cu{sub 2} bond in cuprates using a perturbation scheme that provides an optimal way to account for intra-atomic electron correlations, low-symmetry crystal field, and local spin-orbital contributions with a focus on the oxygen term. The Dzyaloshinsky vector and the corresponding weak ferromagnetic moment are shown to be a superposition of comparable and, sometimes, competing local Cu and O contributions. We predict the effect of oxygen staggered spin polarization in the antiferromagnetic edge-shared CuO{sub 2} chains due to the uncompensated oxygen Dzyaloshinsky vectors. The polarization is perpendicular to both the main chain antiferromagnetic vector and the CuO{sub 2} chain normal. The intermediate {sup 17}O NMR is shown to be an effective tool to inspect the effects of Dzyaloshinsky-Moriya coupling in an external magnetic field. In particular, we argue that the puzzling planar {sup 17}O Knight shift anomalies observed in the paramagnetic phase of the generic Dzyaloshinsky-Moriya antiferromagnetic cuprate La{sub 2}CuO{sub 4} can be assigned to the effect of the field-induced staggered magnetization. Finally, we revisit the effects of symmetric spin anisotropy, in particular, those directly induced by the Dzyaloshinsky-Moriya coupling. The perturbation scheme generalizes the well-known Moriya approach and presents a basis for reliable quantitative estimates for the symmetric partner of the Dzyaloshinsky-Moriya coupling. In contrast to the conventional standpoint, the parameters of the effective two-ion spin anisotropy are shown to incorporate the contributions of a single-ion anisotropy for two-hole configurations at both Cu and O sites.
- OSTI ID:
- 21072461
- Journal Information:
- Journal of Experimental and Theoretical Physics, Vol. 104, Issue 6; Other Information: DOI: 10.1134/S106377610706009X; Copyright (c) 2007 Nauka/Interperiodica; Article Copyright (c) 2007 Pleiades Publishing, Inc; Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-7761
- Country of Publication:
- United States
- Language:
- English
Similar Records
Magnetic susceptibility and low-temperature structure of the linear chain cuprate Sr[sub 2]CuO[sub 3]
Breatherlike electromagnetic wave propagation in an antiferromagnetic medium with Dzyaloshinsky-Moriya interaction