Spin dynamics in the distorted triangular lattice antiferromagnet alpha-SrCr2O4
Abstract
The spin dynamics in the distorted triangular lattice antiferromagnet alpha-SrCr2O4 has been investigated by inelastic neutron scattering on a single crystal. The spin wave dispersion has been mapped out in the (0 k l) and (h k 0) planes, and modeled by spin wave calculations, in order to determine the intraplane and interplane exchange couplings. Comparison with alpha-CaCr2O4 shows that, despite the smaller lattice distortion of alpha-SrCr2O4, the deviation from a perfect triangular lattice still affects the spin dynamics of the Sr compound, with a soft mode, similar to the one observed in the Ca counterpart, being observed in (020). Although alpha-SrCr2O4 is further away from a magnetic phase boundary than its Ca counterpart, its dynamic magnetic properties still show intriguing features, which are discussed as quantum fluctuations arising from a two-magnon continuum.