Temperature−field phase diagram of extreme magnetoresistance

Abstract

The recent discovery of extreme magnetoresistance (XMR) in LaSb introduced lanthanum monopnictides as a new platform to study this effect in the absence of broken inversion symmetry or protected linear band crossing. In this work, we report XMR in LaBi. Through a comparative study of magnetotransport effects in LaBi and LaSb, we construct a temperature−field phase diagram with triangular shape that illustrates how a magnetic field tunes the electronic behavior in these materials. We show that the triangular phase diagram can be generalized to other topological semimetals with different crystal structures and different chemical compositions. By comparing our experimental results to band structure calculations, we suggest that XMR in LaBi and LaSb originates from a combination of compensated electron−hole pockets and a particular orbital texture on the electron pocket. Such orbital texture is likely to be a generic feature of various topological semimetals, giving rise to their small residual resistivity at zero field and subject to strong scattering induced by a magnetic field.extreme magnetoresistance | topological semimetal | orbital texture M aterials with large magnetoresistance (MR) have applications in electronics as magnetic memories (1, 2), in spintronics as magnetic valves (3), and in industry as magnetic sensors or magnetic switches (4, 5). Recent reports of extreme magnetoresistance (XMR) in several nonmagnetic semimetals have attracted attention due to its distinction from giant and collosal MR in magnetic semiconductors (2, 6). XMR is observed in Dirac semimetals such as Na 3 Bi or Cd 3 As 2 (7, 8), Weyl semimetals such as NbP, NbAs, or TaAs (9-11), and layered semimetals such as WTe 2 , NbSb 2 , or PtSn 4 (12-16). The recent discovery of XMR in LaSb that does not belong to any of these categories shows that XMR is a ubiquitous phenomenon observed in seemingly unrelated materials (17). It also clearly underlines that the mechanism for XMR is not understood. The present article is a first attempt to unify the phenomenology of XMR in seemingly unrelated materials, to provide a common phase diagram for XMR, and to elucidate its underlying mechanism. We hope that this will enable theorists to develop a model capable of describing the underlying physics, once all of the salient experimental features are captured.We report the discovery of XMR in LaBi with similar crystal structure and chemical composition to LaSb. Fig. 1 shows the simple rock salt structure of lanthanum monopnictides. Through a comparative study of longitudinal and transverse magnetotransport in LaSb and LaBi, we construct a characteristic triangular T-H phase diagram for XMR in lanthanum monopnictides. Our band structure calculations, quantum oscillations, and Hall Effect measurements suggest that XMR is rooted in a combination of compensated electron−hole pockets and a mixed orbital texture within the electron pockets. The orbital texture is a result of lanthanum d states crossing the pnictogen p states. Spin−orbit coupling then opens a...

Extreme magnetoresistance in magnetic rare-earth monopnictides

“…Starting with sample A1 at T = 2 K in Fig. 2(a), ρ xx (B) shows a rapid positive magnetoresistance reaching 233 500% of its zero-field value at B = 9 T. This XMR behavior is comparable to that seen in WTe 2 [7], LaBi [10,11], and LaSb [9], and significantly larger than that reported previously in CeSb [18,32,[35][36][37] (< 50 000%) and other magnetic RX (see the Supplemental Material, Sec. S4 [26]).…”

“…Combining this set of electronic structure with the exchange field induced by the f -electron degree of freedom suggests RX may therefore be host to topological phases of correlated electrons [18]. This is further enriched by the reports of XMR in LaSb [9,19] and LaBi [10,11,19].…”

“…Alternatively, in nonmagnetic compounds it is known that the combination of carrier compensation and high mobility can lead to nonsaturating MR not possible in single band systems [6]. The latter approach has recently seen renewed interest after the report of MR exceeding 10 5 % in various topological semimetals including WTe 2 [7], PtSn 4 [8], and more recently La(Sb,Bi) [9][10][11]. The extremely large magnetoresistance in these systems, referred as extreme magnetoresistance (XMR), is of fundamental interest in terms of its microscopic origin and potential technological applications.…”

Magnetic field induced strong valley polarization in the three-dimensional topological semimetal LaBi

“…1(a)) and its anisotropic Fermi surface has long been known [12]. Due to the prediction of a non-trivial band structure in LaBi and other lanthanum mono-pnictides [13] there is strongly revived interest in their electronic properties [14][15][16][17][18]. We have shown earlier the realization of quasi-2D transport and excellent magnetoresistance (MR) performance, which could further be enhanced by tuning the magnetic field direction as a result of the large anisotropy in the Fermi surface [14].…”

“…(1) It exhibits a large mobility (~110 4 cm 2 /Vs) and huge MR of the order of 10 5 % at 2 K and 9 T because of charge-carrier compensation and orbital texturing [14,16]. (2) It features several Dirac points and topological surface states.…”