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Anisotropic conductivity in magnetic topological insulators
A Sabzalipour1, J Abouie, S H Abedinpour
1Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan 45137-66731,Iran.
Journal of Physics. Condensed Matter : an Institute of Physics Journal
|February 28, 2015
Summary
We investigated surface conductivity in magnetic topological insulators (TIs). Doping with magnetic impurities creates anisotropic conductivity, with minimum conductivity when impurity spins are perpendicular to the TI surface.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Phenomena
Background:
- Topological insulators (TIs) possess unique surface states with spin-momentum locking.
- Magnetic impurities break time-reversal symmetry, influencing surface electron behavior.
- Standard relaxation time approximations fail due to anisotropic scattering in magnetic TIs.
Purpose of the Study:
- To investigate the surface conductivity of a three-dimensional topological insulator (3D TI) doped with magnetic impurities.
- To develop a theoretical framework applicable to systems where standard approximations are invalid.
- To analyze the dependence of surface conductivity on magnetic impurity properties and bulk magnetization.
Main Methods:
- Utilized the semiclassical Boltzmann approach.
- Employed a generalized relaxation time scheme to account for anisotropic scattering.
- Derived closed-form expressions for relaxation times and analytic formulas for surface conductivity.
Main Results:
- Surface conductivity is anisotropic and strongly dependent on impurity spin orientation and bulk magnetization.
- Minimum surface conductivity occurs when impurity spins are aligned perpendicular to the TI surface.
- Enhanced backscattering probability is observed due to magnetic torque from impurities.
Conclusions:
- The study provides a theoretical model for surface conductivity in magnetic TIs.
- Anisotropic scattering effects due to magnetic impurities are crucial for understanding surface transport.
- Controlling impurity spin orientation offers a potential mechanism for tuning surface conductivity.
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