Jb. Staunton et al., MAGNETIC-ALLOYS, THEIR ELECTRONIC-STRUCTURE AND MICROMAGNETIC AND MICROSTRUCTURAL MODELS, Journal of physics. D, Applied physics (Print), 31(19), 1998, pp. 2355-2375
We present a selective review of electronic structure calculations for
ferromagnetic transition metal alloys. This is work based on the spin
density functional theory of the inhomogeneous electron gas which we
also discuss briefly. These calculations can be used to provide estima
tes, from 'first principles', of the alloys' characteristic properties
such as the saturation magnetization, M-s, and the exchange, A, and a
nisotropy, K, constants as well as their Curie temperatures, T-c, whic
h are all important quantities for the micromagnetic modelling of thes
e materials. The electronic reasons for the simple structure of Slater
-Pauling curves of M-s versus the number of valence electrons are give
n. Anisotropy constants, K, can be evaluated only when relativistic ef
fects upon the electronic motion are included. We review the theory of
finite-temperature metallic magnetism and highlight how the electroni
c structure of metals and alloys in their paramagnetic states can stil
l exhibit a local spin polarization originating from the 'local moment
' spin fluctuations which are excited as the temperature is raised. Fi
nally we show how an alloy's magnetic state can sharply influence the
types of ordered arrangements that the atoms form and conversely how t
he type of compositional structure can affect M-s and K. We include a
discussion of how the compositional structure can be described in term
s of static 'concentration waves'. We illustrate the approach by outli
ning our recent case studies of two iron-rich alloy systems, FeV and F
eAl.