Thermodynamic Signatures of Weyl Fermions in NbP


Thermodynamic Signatures of Weyl Fermions in NbP


Weyl semimetals have attracted considerable attention recently due to their conjectured linear band crossings in momentum space. Broken time-reversal or inversion symmetry lifts the spin-degeneracy at a Dirac node to reveal two Weyl points that are characterized by a right- and left-handedness (chirality). Weyl semimetals are expected to host exotic phenomena, including topological Fermi-arc surface states and unusual magnetotransport properties. The search for such materials, however, is often complicated by the additional presence of trivial (non-Weyl) sections of Fermi surface. Experimental signatures of Weyl fermions are further hindered by a chemical potential that often resides far from the Weyl points.

We studied NbP – a member of the monopnictide Weyl semimetal family – in high magnetic fields in order to isolate the response from the zeroth Landau levels at the Weyl nodes. We identified a sharp change in slope of the magnetic torque at the quantum limit that results from the chemical potential being drawn to the Weyl nodes. Our computed magnetization for a single Weyl pocket is in agreement with the observed magnetic response, confirming the presence of Weyl fermions deep in the quantum limit of NbP.
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QMAT Publications

K. A. Modic, Tobias Meng, Filip Ronning, Eric D. Bauer, Philip J. W. Moll & B. J. Ramshaw

Scientific Reports 9:2095

14 February 2019

DOI: 10.1038/s41598-018-38161-7