Anisotropic magnetoresistance: materials, models and applications

Resistance of certain (conductive and otherwise isotropic) ferromagnets turns out to exhibit anisotropy with respect to the direction of magnetisation: R$_\parallel$ different from R$_\perp$ with reference to the electric current direction. This century-old phenomenon is reviewed both from the perspective of materials and physical mechanisms involved. More recently, this effect has also been extended to antiferromagnets. This opens the possibility for industrial applications reaching far beyond the current ones, e.g. hard drive read heads or position sensors.