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Weyl-mediated helical magnetism in NdAlSi



Jonathan Gaudet, Hung-Yu Yang, Santu Baidya, Baozhu Lu, Guangyong Xu, Yang Zhao, Jose Rodriguez Rivera, Christina M. Hoffman, David E. Graf, Darius H. Torchinsky, Predrag Nikolic, David Vanderbilt, Fazel Tafti, Collin L. Broholm


Emergent relativistic quasiparticles in Weyl semimetals are the source of exotic electronic properties such as surface Fermi arcs, the anomalous Hall effect and negative magnetoresistance, all observed in real materials. Whereas these phenomena highlight the effect of Weyl fermions on the electronic transport properties, less is known about what collective phenomena they may support. Here, we report a Weyl semimetal, NdAlSi, that offers an example. Using neutron diffraction, we found a long-wavelength helical magnetic order in NdAlSi, the periodicity of which is linked to the nesting vector between two topologically non-trivial Fermi pockets, which we characterize using density functional theory and quantum oscillation measurements. We further show the chiral transverse component of the spin structure is promoted by bond-oriented Dzyaloshinskii–Moriya interactions associated with Weyl exchange processes. Our work provides a rare example of Weyl fermions driving collective magnetism.
Nature Materials


Gaudet, J. , Yang, H. , Baidya, S. , Lu, B. , Xu, G. , Zhao, Y. , Rodriguez Rivera, J. , Hoffman, C. , Graf, D. , Torchinsky, D. , Nikolic, P. , Vanderbilt, D. , Tafti, F. and Broholm, C. (2021), Weyl-mediated helical magnetism in NdAlSi, Nature Materials, [online], (Accessed April 17, 2024)
Created August 19, 2021, Updated March 25, 2024