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Weak spin-orbit interactions induce exponentially flat mini-bands in magnetic metals without inversion symmetry

I. Fischer·A. Rosch
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Abstract

In metallic magnets like MnSi the interplay of two very weak spin-orbit coupling effects can strongly modify the Fermi surface. In the absence of inversion symmetry even a very small Dzyaloshinsky-Moriya interaction of strength delta<<1 distorts a ferromagnetic state into a chiral helix with a long pitch of order 1/delta. We show that additional small spin-orbit coupling terms of order delta in the band structure lead to the formation of exponentially flat minibands with a bandwidth of order exp(-1/sqrt(delta)) parallel to the direction of the helix. These flat minibands cover a rather broad belt of width sqrt(delta) on the Fermi surface where electron motion parallel to the helix practically stops. We argue that these peculiar band-structure effects lead to pronounced features in the anomalous skin effect.

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I. Fischer, A. Rosch. 2004-10-06. Weak spin-orbit interactions induce exponentially flat mini-bands in magnetic metals without inversion symmetry. https://doi.org/10.1209/epl%2Fi2004-10174-9

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