Example

Powder average spectrum of CuCrO₂

Samples are not always available in a single-crystal form. Inelastic scattering experiments on polycrystalline compounds can bring useful information nonetheless : basic characteristics, such as the dimensionality of the magnetic lattice, or the anisotropy of the magnetic moment, can be deduced from the general outline of the excitation map in most cases. To go further in the interpretation of a powder excitation spectrum, and in particular to estimate the value of the predominant magnetic coupling and of the magnetic anisotropy term if relevant, it is possible to calculate the powder-averaged spin-wave dispersion with Spinwave. Although this type of calculation cannot by itself lead to the finest details of the exchange Hamiltonian, it can become quite a powerful tool if combined, e.g., with magnetic phase diagrams, allowing to get an overall idea of the nature and the strength of the magnetic couplings in a compound. ...in this example, the same CuCrO₂ Hamiltonian and exchange values as in the spin-spin correlations example is used, but this time a powder-averaged calculation is performed. It is compared in the figure below with the inelastic scattering data of a polycrystalline sample of CuCrO₂ at 5 K (k_f = 2.662 Å^-1). A very good agreement between experimental and calculated maps is observed!

The input file corresponding to this case can be found in the download package.