The chiral anomaly and thermopower of Weyl fermions in the half-Heusler GdPtBi

• Published in: Nature materials Vol. 15; no. 11; pp. 1161 - 1165
• Main Authors: Hirschberger, Max, Kushwaha, Satya, Wang, Zhijun, Gibson, Quinn, Liang, Sihang, Belvin, Carina A., Bernevig, B. A., Cava, R. J., Ong, N. P.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.11.2016; Nature Publishing Group
• Subjects: 639/301/119/2792; 639/301/357/918/1052; 639/766/119/2792; 639/766/483/640; Biomaterials; Condensed Matter Physics; Fermions; letter; Magnetic fields; Magnetoresistance; Magnetoresistivity; Materials Science; Metalloids; Nanotechnology; Nodes; Optical and Electronic Materials; Response functions; Thermoelectricity
• ISSN: 1476-1122; 1476-4660; 1476-4660
• DOI: 10.1038/nmat4684

The half-Heusler GdPtBi is reported to exhibit negative longitudinal magnetoresistance. This is attributed to the chiral anomaly due to the formation of Weyl nodes with an applied magnetic field. The anomaly is also found to suppress the thermopower. The Dirac and Weyl semimetals are unusual materials in which the nodes of the bulk states are protected against gap formation by crystalline symmetry 1 , 2 , 3 , 4 . The chiral anomaly 5 , 6 , predicted to occur in both systems 7 , 8 , 9 , 10 , was recently observed as a negative longitudinal magnetoresistance (LMR) in Na 3 Bi (ref.  11 ) and in TaAs (ref.  12 ). An important issue is whether Weyl physics appears in a broader class of materials. We report evidence for the chiral anomaly in the half-Heusler GdPtBi. In zero field, GdPtBi is a zero-gap semiconductor with quadratic bands 13 , 14 . In a magnetic field, the Zeeman energy leads to Weyl nodes 15 . We have observed a large negative LMR with the field-steering properties specific to the chiral anomaly. The chiral anomaly also induces strong suppression of the thermopower. We report a detailed study of the thermoelectric response function α xx of Weyl fermions. The scheme of creating Weyl nodes from quadratic bands suggests that the chiral anomaly may be observable in a broad class of semimetals.