Extremely large nonsaturating magnetoresistance and ultrahigh mobility due to topological surface states in the metallic Bi2Te3 topological insulator

Abstract

Weak antilocalization (WAL) effects in Bi2Te3 single crystals have been investigated at high and low bulk charge carrier concentrations. At low charge carrier density the WAL curves scale with the normal component of the magnetic field, demonstrating the dominance of topological surface states in magnetoconductivity. At high charge carrier density the WAL curves scale with neither the applied field nor its normal component, implying a mixture of bulk and surface conduction. WAL due to topological surface states shows no dependence on the nature (electrons or holes) of the bulk charge carriers. The observations of an extremely large, non-saturating magnetoresistance, and ultrahigh mobility in the samples with lower carrier density further support the presence of surface states. The physical parameters characterizing the WAL effects are calculated using the Hikami-Larkin-Nagaoka formula. At high charge carrier concentrations, there is a greater number of conduction channels and a decrease in the phase coherence length compared to low charge carrier concentrations. The extremely large magnetoresistance and high mobility of topological insulators have great technological value and can be exploited in magneto-electric sensors and memory devices.

Two-dimensional superconductivity and magnetotransport from topological surface states in AuSn4 semimetal

“…It is known that a sharp magnetoresistance dip at low temperatures indicates the presence of a WAL effect; when we increase the temperature, the magnetoresistance dip broadens at the low field due to the decrease of the phase coherence length at higher temperatures 48 . Similar types of magnetoresistance behavior without any sign of saturation have been seen in topological materials [48][49][50] . In particular, Shrestha et al 49 have recently shown extremely large nonsaturating magnetoresistance (540% at T = 2 K under 7 T) and ultrahigh Hall mobility (4.5 × 10 4 cm 2 V −1 s −1 at T = 5 K) due to topological surface states in the metallic Bi 2 Te 3 topological insulator 49 , results which are comparable with those of magnetoresistance ≈ 650% at 2.5 K under 6 T and Hall mobility ≈ 3.5 × 10 3 cm 2 V −1 s −1 at T = 2.5 K observed on our AuSn 4 single crystals (for details, see Supplementary Note 3).…”

“…Similar types of magnetoresistance behavior without any sign of saturation have been seen in topological materials [48][49][50] . In particular, Shrestha et al 49 have recently shown extremely large nonsaturating magnetoresistance (540% at T = 2 K under 7 T) and ultrahigh Hall mobility (4.5 × 10 4 cm 2 V −1 s −1 at T = 5 K) due to topological surface states in the metallic Bi 2 Te 3 topological insulator 49 , results which are comparable with those of magnetoresistance ≈ 650% at 2.5 K under 6 T and Hall mobility ≈ 3.5 × 10 3 cm 2 V −1 s −1 at T = 2.5 K observed on our AuSn 4 single crystals (for details, see Supplementary Note 3). We may also note that, due to the non-negligible contribution of transverse resistivity, as arising from the high Hall mobility, the original experimental resistivity data were asymmetric in the field.…”

“…6a. The temperature dependence of the H* suggests the existence of a linear-dispersion electronic band in AuSn 4 , as seen in topological materials [48][49][50] . Now that the normal-state transport property of AuSn 4 indicates a crossover from a WAL-dominant MR(H) to a linear and non-saturating MR(H), the fielddependent transverse magnetoconductivity will be analyzed within the framework of a WAL electrical transport.…”

Modeling of magneto-conductivity of bismuth selenide: a topological insulator

“…Experimentally, the SS in topological insulators can be determined by Scanning Tunneling Microscopy (STM) and Angle-Resolved Photoemission Spectroscopy (ARPES) [5,17,18]. Numerous bismuth (Bi)-based materials such as Bi 1−x Sb x , Bi 2 Te 3, and Bi 2 Se 3 have been experimentally verified to possess these topological SS [19,20], and their existence in these 3D binaries TIs has been verified through magneto-transport measurements in thin films [21], and single crystals [22]. The surface states of these topological insulators, i.e., Bi 2 Te 3 and Bi 2 Se 3, are verified to possess only one helical Dirac cone [4,5,18], and WAL is intrinsic to them.…”

Accessing topological surface states and negative MR in sculpted nanowires of Bi2Te3 at ultra-low temperature

“…Our results indicate that LMR (linear magnetoresitance) observed at high temp range (>2K) is not sufficient for accessing the TSS and measurements at ultra low temp give more access to TSS. In the literature, MR measurements showing WAL effects were heavily used to prove the transport through TSS 13,14,19,[29][30][31] .…”