Transport in magnetic Weyl semimetals (WSMs) generally involves three degrees of freedom -- charge, valley, and spin. In this work, we systematically investigate the magnetic noise induced by the fluctuations of the charge current, the valley (axial) current, and the magnetic order. We show that these three flavors of the magnetic noise have distinctively different spectral characters. Our work provides a theoretical guidance for the noninvasive study of valley transport in magnetic WSMs by magnetic noise spectroscopy, for example, using nitrogen-vacancy centers. Our approach could also be generalized to discuss WSMs with other types of broken symmetries and topological semimetals in general.
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