Resistivity plateau and extreme magnetoresistance in LaSb

• Published in: Nature physics 2016-03, Vol.12 (3), p.272-277
• Main Authors: Tafti, F. F., Gibson, Q. D., Kushwaha, S. K., Haldolaarachchige, N., Cava, R. J.
• Format: Article
• Language: English
• Subjects: 119/118; 639/301/119/2792; 639/766/119/2792; Atomic; Breaking; Classical and Continuum Physics; Complex Systems; Condensed Matter Physics; Electrical resistivity; Fermi surfaces; Insulation; Inversions; Magnetoresistance; Mathematical and Computational Physics; Metalloids; Metals; Molecular; Optical and Plasma Physics; Physics; Rocks; Symmetry; Theoretical; Time; Topology
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/nphys3581

Time reversal symmetry (TRS) protects the metallic surface modes of topological insulators (TIs). The transport signature of such surface states is a plateau that arrests the exponential divergence of the insulating bulk with decreasing temperature. This universal behaviour is observed in all TI candidates ranging from Bi 2 Te 2 Se to SmB 6 . Recently, extreme magnetoresistance (XMR) has been reported in several topological semimetals which exhibit TI universal resistivity behaviour only when breaking time reversal symmetry, a regime where TIs theoretically cease to exist. Among these materials, TaAs and NbP are nominated as Weyl semimetals owing to their lack of inversion symmetry, Cd 3 As 2 is known as a Dirac semimetal owing to its linear band crossing at the Fermi level, and WTe 2 is termed a resonant compensated semimetal owing to its perfect electron–hole symmetry. Here we introduce LaSb, a simple rock-salt structure material that lacks broken inversion symmetry, perfect linear band crossing, and perfect electron–hole symmetry yet exhibits all the exotic field-induced behaviours of these more complex semimetals. It shows a field-induced universal TI resistivity with a plateau at roughly 15 K, ultrahigh mobility of carriers in the plateau region, quantum oscillations with the angle dependence of a two-dimensional Fermi surface, and XMR of about one million percent at 9 T. Owing to its structural simplicity, LaSb represents an ideal model system to formulate a theoretical understanding of the exotic consequences of breaking time reversal symmetry in topological semimetals. A series of transport experiments on lanthanum antimonide reveal a plateau in its resistivity and an extremely large magnetoresistance that are consistent with topologically protected electronic states.