Interplanar coupling-dependent magnetoresistivity in high-purity layered metals

• Published in: Nature communications Vol. 7; no. 1; p. 10903
• Main Authors: Kikugawa, N., Goswami, P., Kiswandhi, A., Choi, E. S., Graf, D., Baumbach, R. E., Brooks, J. S., Sugii, K., Iida, Y., Nishio, M., Uji, S., Terashima, T., Rourke, P.M.C., Hussey, N. E., Takatsu, H., Yonezawa, S., Maeno, Y., Balicas, L.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 29.03.2016; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/1023/1026; 639/301/119/997; 639/766/483/481; Humanities and Social Sciences; MATERIALS SCIENCE; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms10903

The magnetic field-induced changes in the conductivity of metals are the subject of intense interest, both for revealing new phenomena and as a valuable tool for determining their Fermi surface. Here we report a hitherto unobserved magnetoresistive effect in ultra-clean layered metals, namely a negative longitudinal magnetoresistance that is capable of overcoming their very pronounced orbital one. This effect is correlated with the interlayer coupling disappearing for fields applied along the so-called Yamaji angles where the interlayer coupling vanishes. Therefore, it is intrinsically associated with the Fermi points in the field-induced quasi-one-dimensional electronic dispersion, implying that it results from the axial anomaly among these Fermi points. In its original formulation, the anomaly is predicted to violate separate number conservation laws for left- and right-handed chiral (for example, Weyl) fermions. Its observation in PdCoO 2 , PtCoO 2 and Sr 2 RuO 4 suggests that the anomaly affects the transport of clean conductors, in particular near the quantum limit. In Weyl semimetals, unusual electronic transport phenomena are predicted to occur, such as an axial anomaly which violates the conservation of chiral fermions. Here, the authors evidence such behaviour via the occurrence of negative magnetoresistance in layered high-purity non-magnetic metals.