Magnetoresistance - A new spin on magnets

Abstract

Just like photons propagating through space, electrons flowing through a crystalline metal travel in simple plane waves. Add sufficient disorder and those electrons are no longer free to fly. Rather they will diffuse from scatterer to scatterer, performing a random walk through the 'dirty' metal. At very low temperatures, near absolute zero, the phase of the electron becomes important and quantum interference effects manifest themselves. At the quantum level both the amplitude and phase of the electronic wavefunction are needed to describe the electron completely. On page 581 of this issue, Manyala et al. describe how these quantum interference effects not only dominate the behaviour of a metallic ferromagnet (a material similar to iron) at the relatively scorching temperature of liquid nitrogen, but might account for an entirely new mechanism behind the magnetic response of solids.

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