Transitions of the Néel vector in spintronics

We study transitions of the Néel vector out of a metastable state to a more stable one in the presence of a polarized current. The discussion is general although the system considered is an antiferromagnetic spintronic. The presence of the current allows one to study transitions of the Néel vector as a function of temperature with the effect of dissipation that can be varied from positive to negative depending on the sign of the current. This is different than the usual case where one only has one type of positive dissipation when only magnetic field is being applied to an antiferromagnet. Using the method of path integral, we derive the expression for the rate of transitions of the Néel vector. A cross-over temperature T ₀ between quantum and thermal transitions is determined. The expressions for the rates of quantum transitions below the cross-over temperature, and of thermal transitions at and above it are presented. The expression of the polarized current that diminishes the effect of dissipation is also presented as a function of temperature.