@article{7068, abstract = {Electrons in materials with linear dispersion behave as massless Weyl- or Dirac-quasiparticles, and continue to intrigue due to their close resemblance to elusive ultra-relativistic particles as well as their potential for future electronics. Yet the experimental signatures of Weyl-fermions are often subtle and indirect, in particular if they coexist with conventional, massive quasiparticles. Here we show a pronounced anomaly in the magnetic torque of the Weyl semimetal NbAs upon entering the quantum limit state in high magnetic fields. The torque changes sign in the quantum limit, signalling a reversal of the magnetic anisotropy that can be directly attributed to the topological nature of the Weyl electrons. Our results establish that anomalous quantum limit torque measurements provide a direct experimental method to identify and distinguish Weyl and Dirac systems.}, author = {Moll, Philip J. W. and Potter, Andrew C. and Nair, Nityan L. and Ramshaw, B. J. and Modic, Kimberly A and Riggs, Scott and Zeng, Bin and Ghimire, Nirmal J. and Bauer, Eric D. and Kealhofer, Robert and Ronning, Filip and Analytis, James G.}, issn = {2041-1723}, journal = {Nature Communications}, publisher = {Springer Nature}, title = {{Magnetic torque anomaly in the quantum limit of Weyl semimetals}}, doi = {10.1038/ncomms12492}, volume = {7}, year = {2016}, }