Abstract
Phase boundaries, Tc vs H, of isotropic antiferromagnets are discussed. The Fisher-Nelson-Kosterlitz predictions for the effect of a spin-dimensionally crossover on Tc(H) are summarized. The stringent experimental requirements for testing these predictions are reviewed. Results for Tc(H) in the very-low-anisotropy cubic antiferromagnets RbMnF3 and KNiF3 confirm the theoretical predictions for the case of a Heisenberg-to-XY crossover. The RbMnF3 data give a crossover exponent φ which agrees with theory. Results for Tc(H) in the easy-plane antiferromagnet CsMnF3 are presented. The data when H↘ is in the easy plane are consistent with an XY-to-Ising crossover, and give φ=1.185±0.03. The results when H↘ is perpendicular to the easy plane are interpreted in terms of a virtual bicritical point at some negative value of H2.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
