&&ReWrAp:HEADERFOOTER:0:ReWrAp&&

Date of Award

9-1976

Degree Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

Supervisor

M.F. Collins

Abstract

Two of the magnetic properties of antiferromagnet, CsMnF₃, were studied by thermal neutron scattering techniques.

Spin wave-dispersion curves, along the two high symmetry directions (00ξ) and (ξ00), were determined and were satisfactorily fitted to a theoretical model with two nearest neighbour exchange constants, J₁₂ = 0.134±.003 THz and J₂₃ = 0.094±.0105 THz, and one second nearest neighbour exchange constant, J₃₅=-0.0138±.003 THz. The spin wave properties can be described in terms of an effective anisotropy field of -2700±900 Oe along the crystal c axis. This field constrains the spins to the basal plane of the crystal. The calculations show that magnetic dipole-dipole interactions, alone, provide enough anisotropy to account for the observed results.

The sublattice magnetization, over the temperature range of 6.8 K to 72.2 K, was measured. This shows a critical phase transition with a critical exponent β given by β = 0.317±.009.

Included in

Physics Commons

Share

COinS