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arXiv · 1803.09117

Topological order generated by random field in a 2D exchange model

E. M. Chudnovsky·D. A. Garanin
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Abstract

We study a 2D exchange model with a weak static random field on lattices containing over one hundred million spins. Ferromagnetic correlations persist on the Imry-Ma scale inversely proportional to the random-field strength and decay exponentially at greater distances. We find that the average energy of the correlated area is close to the ground-state energy of a skyrmion, while the topological charge of the area is close to $\pm 1$. Correlation function of the topological charge density exhibits oscillations with a period determined by the ferromagnetic correlation length, while its Fourier transform exhibits a maximum. These findings suggest that static randomness transforms a 2D ferromagnetic state into a skyrmion-antiskyrmion glass.

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E. M. Chudnovsky, D. A. Garanin. 2018-03-24. Topological order generated by random field in a 2D exchange model. https://doi.org/10.1103/physrevlett.121.017201

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