Leopold Infeld Colloquium

A scaling theory is presented for quantum criticality in an open(coupled to reservoirs) itinerant electron ferromagnet, withnonequilibrium drive provided by current flow across the system.Both departures from equilibrium at conventional (equilibrium)quantum critical points and the physics of phase transitionsinduced by the nonequilibrium drive are studied. The theory isextended for a coupled bilayer system of itinerant electronferromagnets in which one layer is driven out of equilibrium bycurrent flow along the system. We discuss the interplayof two different dynamical scales that arises in the presence oftwo bosonic fields, which are related to the magnetizationfluctuations of the two layers. In both systems, the resultsare presented for order parameters with Ising symmetry.