Criticality in inhomogeneous magnetic systems: application to quantum ferromagnets.
We consider a phi4 theory with a position-dependent distance from the critical point. One realization of this model is a classical ferromagnet subject to nonuniform mechanical stress. We find a sharp phase transition where the envelope of the local magnetization vanishes uniformly. The first-order transition in a quantum ferromagnet also remains sharp. The universal mechanism leading to a tricritical point in an itinerant quantum ferromagnet is suppressed, and in principle, one can recover a quantum critical point with mean-field exponents. Observable consequences of these results are discussed.
Belitz
D
D
Department of Physics and Materials Science Institute, University of Oregon, Eugene, OR 97403 USA.
Kirkpatrick
T R
TR
Saha
Ronojoy
R