Vortex lattice in two-dimensional chiral XY ferromagnets and the inverse Berezinskii-Kosterlitz-Thouless transition

摘要

In this Rapid Communication we will show that, in the presence of a properly modulated Dzyaloshinskii-Moriya(DM) interaction, a U(1) vortex-antivortex lattice appears at low temperatures for a wide range of the DM interaction. Even more, in the region dominated by the exchange interaction, a standard Berezinskii-Kosterlitz-Thouless (BKT) transition occurs. In the opposite regime, the one dominated by the DM interaction, a kind of inverse BKT transition takes place. As temperature rises, the vortex-antivortex lattice starts melting by the annihilation of vortex-antivortex pairs, in a sort of "inverse" BKT transition.