Saturday, October 2, 2010

Anomalous magnetoresistance in the pseudogap state

Previously I wrote a post about a wide range of strongly correlated electron materials that exhibit a very puzzling and unexplained magnetoresistance. In particular, the dependence on the direction of the magnetic field is the opposite to what one expects for the Lorentz force.

I recently became aware of another example, the underdoped cuprate superconductor
The angular dependence of the intra-layer magnetoresistance is described in this PRL and interlayer magnetoresistance data is available in a 2006 PRB.

The authors suggest that the anomalous angular dependence arises because the magnetoresistance is not dominated by quasi-particles but rather the flux flow from fluctuating superconducting vortices associated with pseudogap state.

There is an alternative explanation of the data due to Dora, Maki, and Virosztek. They consider an underlying d-density wave state [which has a pseudogap]. They claim that their theory describes some of the other materials in my original post and the heavy fermion material CeCoIn5. Hence, I need to understand this theory better. One question I have is how it deals with the violation of Kohler's rule. [I suspect it comes about due to thermal excitations across the pseudogap].

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