Observation of planar Hall effect in topological insulator—Bi2Te3

Abstract

Planar Hall effect (PHE) in topological insulators (TIs) is discussed as an effect that stems mostly from conduction due to topologically protected surface states. Although surface states play a critical role and are of utmost importance in TIs, our present study in Bi 2 Te 3 thin films reflects the need for considering the bulk conduction in understanding the origin of PHE in TIs. This necessity emerges from our observation of an unconventional increase in the PHE signal with TI thickness and temperature where the bulk effect takes over. Here, we find an enhancement in the PHE amplitude by doubling the Bi 2 Te 3 film-thickness on the Si (111) substrate-from % 1.9 nX m in 14 quintuple layer (QL) to % 3.1 nX m in 30 QL devices at B ¼ 5 T. Also, the PHE amplitude in the 30 QL Bi 2 Te 3 films grown on two different substrates, viz., Si (111) and Al 2 O 3 (0001), shows an increase with temperature. Our experiments indicate that the contribution of bulk states to PHE in TIs could be significant.

Emergence of Unconventional Interfacial Magnetic Phenomenon in Topological Insulator-Based Magnetic Heterostructures

“…3 (e), which is different from the proposed anomalous PHR in two dimensional systems [35][36][37]. Outside region III, there is no significant ϕ dependence of R xx and R xy , conventional PHE signal of Bi 2 Te 3 is observed at high fields (B ≥ 1 T -see SI) [28].…”

“…Planar Hall effect (PHE) refers to the development of a transverse voltage in response to longitudinal current and an in-plane magnetic field B, such that the influence of Lorentz force is absent [27,28]. In a conventional ferromagnet or a TI, PHE depends on ϕ, the in-plane angle between current and magnetic field, as R xy ∝ sin 2ϕ and R xx ∝ cos 2 ϕ, where R xy is the planar Hall resistance (PHR) [10,29] and R xx is the planar magneto-resistance (PMR) [30].…”

Quantum Transport and Potential of Topological States for Thermoelectricity in Bi$_2$Te$_3$ Thin Films

“…Hall effect [121], weak antilocalization [122,123] and Shubnikov-de Haas (SdH) oscillations [84,124] have been reported in magnetotransport experiments on Bi 2 Te 3 thin films. In addition, micro-and nano-structured Bi 2 Te 3 thin films demonstrated gate-tunable changes in transport properties, the full depletion of bulk carriers, as well as the successful realization of combined gate-tunable Josephson supercurrents and normal-state transport of Josephson junctions and Hall bar devices fabricated sideby-side [21,125].…”

“…(a) Reprinted and partly adapted with permission from [40], © 2018 American Physical Society. (b)-(c) Reprinted from[131]; and (d)-(f) from[121] with permission of AIP Publishing.…”

Quantum oscillations of the nonlinear planar effects signifying chiral anomaly in Weyl Semimetals

“…However, it has been gradually realized that both these two planar magneto transport effects, namely, the positive LMC and PHE, are not sufficient transport signatures to guarantee the presence of CA in WSMs. Recently, it has been reported that similar planar transport behaviors can also arise through various extrinsic mechanisms [11,[15][16][17][18][19] and even appear in * ygyao@bit.edu.cn materials without any Weyl nodes [20][21][22][23][24][25][26][27][28][29][30][31][32]. In addition, Weyl nodes themselves do not always exhibit positive LMC.…”