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Abstract We present room-temperature measurements of magnon spin diffusion in epitaxial ferrimagnetic insulator MgAl 0.5 Fe 1.5 O 4 (MAFO) thin films near zero applied magnetic field where the sample forms a multi-domain state. Due to a weak uniaxial magnetic anisotropy, the domains are separated primarily by 180° domain walls. We find, surprisingly, that the presence of the domain walls has very little effect on the spin diffusion – nonlocal spin transport signals in the multi-domain state retain at least 95% of the maximum signal strength measured for the spatially-uniform magnetic state, over distances at least five times the typical domain size. This result is in conflict with simple models of interactions between magnons and static domain walls, which predict that the spin polarization carried by the magnons reverses upon passage through a 180° domain wall. 

Topological Dirac semimetal α-Sn exhibits unexpectedly large bilinear magnetoelectric resistance at room temperature. 

This article reports damping enhancement in a ferromagnetic NiFe thin film due to an adjacent α‐Sn thin film. Ferromagnetic resonance studies show that an α‐Sn film separated from a NiFe film by an ultrathin Ag spacer can cause an extra damping in the NiFe film that is three times bigger than the intrinsic damping of the NiFe film. Such an extra damping is absent in structures where the α‐Sn film interfaces directly with a NiFe film, or is replaced by a β‐Sn film. The data suggest that the extra damping is associated with topologically nontrivial surface states in the topological Dirac semimetal phase of the α‐Sn film. This work suggests that, like topological insulators, topological Dirac semimetal α‐Sn may have promising applications in spintronics.