Springer LINK: The European Physical Journal B - Abstract Volume 5 Issue 1 (1998) pp 15-22

The European Physical Journal B

ISSN: 1434-6028 (printed version)
ISSN: 1434-6036 (electronic version)

Table of Contents

Abstract Volume 5 Issue 1 (1998) pp 15-22

Spin correlations in the two-dimensional spin-5/2 Heisenberg antiferromagnet $\mathsf{Rb_2MnF_4}$

Y.S. Lee (1), M. Greven (1) (a), B.O. Wells (1), R.J. Birgeneau (1) (b), G. Shirane (2)

(1) Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
(2) Department of Physics, Brookhaven National Laboratory, Upton, NY 11973, USA

Received: 3 March 1998 / Received in final form: 4 May 1998 / Accepted: 19 May 1998

Abstract: We report a neutron scattering study of the instantaneous spin correlations in the two-dimensional spin S=5/2 square-lattice Heisenberg antiferromagnet Rb₂MnF₄. The measured correlation lengths are quantitatively described, with no adjustable parameters, by high-temperature series expansion results and by a theory based on the quantum self-consistent harmonic approximation. Conversely, we find that the data, which cover the range from about 1 to 50 lattice constants, are outside of the regime corresponding to renormalized classical behavior of the quantum non-linear $\sigma$ model. In addition, we observe a crossover from Heisenberg to Ising critical behavior near the Néel temperature; this crossover is well described by a mean-field model with no adjustable parameters.

PACS. 75.10.Jm Quantized spin models - 75.25.+z Spin arrangements in magnetically ordered materials (including neutron and spin-polarized electron studies, synchrotron-source X-ray scattering, etc.) - 75.30.Gw Magnetic anisotropy

(a) Present address: Department of Applied Physics and Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, CA 94305, USA.
(b) email: robertjb@mit.edu

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