Disordered local moment picture

The disordered local moment (DLM) picture is a method, in theoretical solid state physics, for describing the electronic structure of a magnetic material at a finite temperature, where a probability distribution of sizes and orientations of atomic magnetic moments must be considered.

The underlying assumption of the DLM picture is similar to the Born-Oppenheimer approximation for the separation of solution of the ionic and electronic problems in a material.

The picture is typically based on density functional theory (DFT) calculations of the electronic structure of materials.

Most frequently, DLM calculations employ either the Korringa–Kohn–Rostoker (KKR)[6] (sometimes referred to as multiple scattering theory) or linearised muffin-tin orbital (LMTO) formulations of DFT, where the coherent potential approximation (CPA) can be used to average over multiple orientations of magnetic moment.

However, the picture has also been applied in the context of supercells containing appropriate distributions of magnetic moment orientations.

Illustrations of a magnetic material with varying degrees of magnetic order parameter.
Illustrations of a magnetic material with varying magnetic order parameter, , and an indicative temperature, , as compared to the material's Curie (or Néel) temperature, . The disordered local moment (DLM) picture provides a means by which to describe thermally induced spin fluctuations within the tenets of density functional theory .