Thermally or Magnetically Induced Polarization Reversal in the Multiferroic CoCr(2)O(4)

Abstract

We report the unexpected evolution, with thermal and magnetic-field (H) variations, of the interrelation between the polarization P, magnetization M, and spiral wave vector Q in CoCr(2)O(4), which has a ferrimagnetic conical-spiral magnetic order. For example, P suddenly jumps and changes its sign at the magnetic lock-in transition (T(L)) with thermal variation, or with isothermal variation of H (without changing its direction) at T(L), which surprisingly occurs without change in spiral handedness (i.e., the sign of Q). The presence of multiple spiral sublattices may be behind this unusual behavior.