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arXiv · 2008.07583

Scattering of magnons at graphene quantum-Hall-magnet junctions

Nemin Wei·Chunli Huang·Allan H. MacDonald
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Abstract

Motivated by recent non-local transport studies of quantum-Hall-magnet (QHM) states formed in monolayer graphene's $N=0$ Landau level, we study the scattering of QHM magnons by gate-controlled junctions between states with different integer filling factors $ν$. For the $ν=1|-1|1$ geometry we find magnons are weakly scattered by electric potential variation in the junction region, and that the scattering is chiral when the junction lacks a mirror symmetry. For the $ν=1|0|1$ geometry, %in which the scattering region contains a $ν=0$ canted antiferromagnet, we find that kinematic constraints completely block magnon transmission if the incident angle exceeds a critical value. Our results explain the suppressed non-local-voltage signals observed in the $ν=1|0|1$ case. We use our theory to propose that valley-waves generated at $ν=-1|1$ junctions and magnons can be used in combination to probe the spin/valley flavor structure of QHM states at integer and fractional filling factors.

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Nemin Wei, Chunli Huang, Allan H. MacDonald. 2020-08-17. Scattering of magnons at graphene quantum-Hall-magnet junctions. https://doi.org/10.1103/physrevlett.126.117203

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