Harvard Condensed Matter Theory Seminars

Juerg Froehlich

Random Zeeman interactions and Anderson Localization

I discuss recent experimental results on Eu_x Ca_{1-x} B_6 found in the group of my colleague H.R. Ott at ETH. I then interpret these results in terms of a tight-binding model with a weakly filled conduction band. As a consequence of Hund's rule, electrons in the conduction band experience random Zeeman interactions with the localized spins carried by the Eu atoms. This causes localization. When a large external magnetic field is turned on the localized spins align in the direction of the external field. This causes delocalization, and the material becomes a conductor. (This is a report on work in progress.)

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