Spin waves in the oblique antiferromagnetic phase of K2CoxFe1-xF4: a mixed magnetic system with competing spin anisotropies

Abstract

The spin waves in the d=2 mixed antiferromagnet K2CoxFe1-xF4 have been investigated using inelastic neutron scattering for a sample with a concentration x=0.27. K2CoxFe1-xF4 is a system with competing orthogonal spin anisotropies and for temperatures below TL=27+or-2 K the x=0.27 sample is in the oblique antiferromagnetic (OAF) phase. Emphasis has been placed on the low-temperature spin wave dispersion relation which is revealed to have at least two low-frequency branches, and on the effect of temperature on the lower of these branches at small reduced wave-vector as the temperature approaches TL from below.