Field Dependence of the Magnetization and SpinWave Correlations in Ferromagnetic CrBr_{3}
Abstract
Using the Cr^{53} NMR, the field dependence of the magnetization M(T_{0},H) at elevated temperatures of singlecrystal ferromagnetic CrBr_{3} has been determined. While an accurate fit to the M(T_{0},H)vsH data can be obtained using a twoexchangeparameter firstorder renormalized spinwave theory, the parameters required differ appreciably from those required for an accurate fit to the previously obtained M(T,0)vsT data with the same theory. A tmatrix twoparametermodel theory, correct to lowest order in the magnon density, but to all orders in the magnonmagnon interaction, was constructed. Although both the firstorder and tmatrix corrections to the spinwave energies are sizable, the full tmatrix results only change the large firstorder corrections to M(T,H) by 15%. However, even if one employs the full tmatrix renormalization there are no pairs of values of the two exchange parameters which simultaneously fit the M(T,0)vsT and M(T_{0},H)vsH data. We attribute the inability of the more sophisticated theory to provide agreement with measurements of more than one thermodynamic function to be an inadequacy of the twoparameter model rather than an intrinsic failure of the theoretical approach.
 Publication:

Physical Review B
 Pub Date:
 March 1971
 DOI:
 10.1103/PhysRevB.3.1677
 Bibcode:
 1971PhRvB...3.1677C