Abstract

When external stimuli or varying temperature alter its magnetic properties a metal’s complex electronic fluid with its emergent magnetic ‘local moments’ transforms. The coupled itinerant electrons and more localised spin degrees of freedom have a profound effect on structure, electronic transport, and so on. Over the last few years the Density Functional Theory-based Disordered Local Moment Theory (DLM) has proved to be a successful method [1-4] to describe magnetic materials from this standpoint. The theory will be described and shown to provide a free energy function of local moment order parameters, determined by and affecting the underlying spin-polarised electronic structure of a material. The versatility of the approach will be illustrated by recent applications to the magnetic order and its link to the Fermi surfaces of the heavy rare earth metals [3], the tricritical metamagnetism in frustrated antiferromagnets [5,6] with rich magnetic-strain phase diagrams and associated caloric effects, and finally to the magnetic properties of rare earth – transition metal permanent magnets such as SmCo5 [4,5] focussing on intrinsic temperature dependent ferrimagnetism, saturation magnetisation and magnetic anisotropy.

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