Strong spin-orbit coupling and Zeeman spin splitting in angle dependent magnetoresistance of Bi2Te3

Abstract

We have studied angle dependent magnetoresistance of Bi2Te3 thin film with field up to 9 T over 2–20 K temperatures. The perpendicular field magnetoresistance has been explained by the Hikami-Larkin-Nagaoka theory alone in a system with strong spin-orbit coupling, from which we have estimated the mean free path, the phase coherence length, and the spin-orbit relaxation time. We have obtained the out-of-plane spin-orbit relaxation time to be small and the in-plane spin-orbit relaxation time to be comparable to the momentum relaxation time. The estimation of these charge and spin transport parameters are useful for spintronics applications. For parallel field magnetoresistance, we have confirmed the presence of Zeeman effect which is otherwise suppressed in perpendicular field magnetoresistance due to strong spin-orbit coupling. The parallel field data have been explained using both the contributions from the Maekawa-Fukuyama localization theory for non-interacting electrons and Lee-Ramakrishnan theory of electron-electron interactions. The estimated Zeeman g-factor and the strength of Coulomb screening parameter agree well with the theory. Finally, the anisotropy in magnetoresistance with respect to angle has been described by the Hikami-Larkin-Nagaoka theory. This anisotropy can be used in anisotropic magnetic sensor applications.

Influence of an Anomalous Temperature Dependence of the Phase Coherence Length on the Conductivity of Magnetic Topological Insulators

“…where i runs over the number of independent WL and WAL 2D transport channels. F i is the Coulomb screening factor (0 < F i < 1), scaled by a factor η i H [15,28,32]. T E is the characteristic temperature below which logarithmic EEI corrections dominate σ xx (T ) [34], which is typically in the range of 6 -10 K [34,35] for Bi 2 Se 3 , in line with our findings.…”

“…We start our discussion with pure Bi 2 Se 3 , where at T = 1.8 K and B ≤ 1 T (β = 0) we derive values α = (−0.32±0.03) and l Φ = (137±5) nm, which are comparable to those found in most previous reports [27,28]. The fact that α < 0 but significantly above − 1 2 may be indicative of the presence of WL contribution from bulk channels [29].…”

Detection of current induced spin polarization in epitaxial Bi2Te3 thin film

“…The transverse Hall resistance and the longitudinal resistance are measured using Ti/Au contacts deposited on the patterned thin film. and the bulk states are occupied [32][33][34]. The conductivity σ(B) obtained from the longitudinal resistance shows the signature of weak antilocalization (WAL).…”

“…2(b), we obtain l φ = 121 nm and α = −0.46. Although, the value of α ≈ −1/2 implies that both the surface and the bulk states are coupled and behave like a single phase coherent channel [32,33]; it is possible that only the spin polarized surface state, and not the bulk states, contribute significantly to the spin signal [8,[11][12][13]19]. In our thin film, the 3D electron concentration n 3D = 3.5 × 10 20 cm −3 is close to the saturated electron concentration n sat = 4 × 10 20 cm −3 in Bi 2 Te 3 that corresponds to the stabilized Fermi level [25].…”

“…The details of the growth and initial characterizations have been reported [32,33]. The transport measurements are performed in a Physical Property Measurement System capable of cooling down to 2 K with magnetic field up to 9 T. The thin film is patterned in a Hall bar geometry with standard etching and lithography.…”