Variation of the Neel temperature of the one-dimensional antiferromagnet K2FeF5with applied field

Abstract
Single-crystal Mossbauer measurements show that the Neel temperature of K2FeF5 increases for magnetic fields applied perpendicular to the easy axis and decreases for magnetic fields applied parallel to the easy axis. This behaviour is consistent with theoretical results for a quasi-one-dimensional Heisenberg antiferromagnet. Calculations of the magnetic phase diagram have been performed and these are in excellent agreement with the experimental data.