Double-loop hysteresis in tetragonal KTa0.58Nb0.42O3 correlated to recoverable reorientations of the asymmetric polar domains

KTa1−xNbxO3 single crystals are typically regarded as normal ferroelectrics. Such crystals are thought to undergo a paraelectric-ferroelectric phase transition from the cubic to the tetragonal phase where generally a single hysteresis loop is expected. Nevertheless, a double-loop hysteresis is clearly observed in the tetragonal phase of KTa0.58Nb0.42O3. Our investigations reveal further that the double loop exhibits good ergodicity during changes in temperature under various applied electric fields. The origin of this unusual double-loop hysteresis in tetragonal KTa0.58Nb0.42O3 is revealed with the recoverable reorientation of the asymmetric polar domains.