Tipping without Flipping: A Novel Metastable "Tilted" State in Anisotropic Ferromagnets in External Fields

Abstract

We show that in suitable anisotropic ferromagnets, both stable and metastable ``tilted'' phases occur, in which the magnetization ${\vec M}$ makes an angle between zero and $180$ degrees with the externally applied ${\vec H}$. Tuning either the magnitude of the external field or the temperature can lead to continuous transitions between these states. A unique feature is that one of these transitions is between two {\it metastable} states. Near the transitions the longitudinal susceptibility becomes anomalous with an exponent which has an {\it exact} scaling relation with the critical exponents.