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Conserved Ordering Dynamics of Heisenberg Spins with Torque

Jayajit Das·Madan Rao
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Abstract

We show that a torque induced by the local molecular field drives the zero-temperature ordering dynamics of a conserved Heisenberg magnet to a new fixed point, characterised by exponents z=2 and $λ\approx 5.15$. Numerical solutions of the Langevin equation indicate that theories using a Gaussian closure are inconsistent even when the torque is absent. The torque is relevant even for quenches to T_c, with exponents $z=4-ε/2$ and $λ= d$ (where $ε= 6-d$). Indeed $λ$ is always equal to d for quenches to T_c whenever the order parameter is conserved.

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Jayajit Das, Madan Rao. 1999-03-02. Conserved Ordering Dynamics of Heisenberg Spins with Torque. https://arxiv.org/abs/cond-mat/9903041

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