Special Condensed Matter Seminar - Abhinav Kandala, Penn State U. - "Engineering dissipation-less transport in magnetic topological insulator systems"

Thu, Apr 9, 2015, 1:00 pm to 2:00 pm
Jadwin 111
The mass domain wall of a 2D Dirac system has been long predicted to carry a chiral 1D mode. More recently, magnetic perturbations to the Dirac surface states of 3D topological insulators have created a practical route for the experimental realization of such 1D dissipation-less modes, and created a rich playground for a host of other exotic quantum phenomena. I present two different schemes for probing these effects in electrical transport devices – interfacing with insulating ferromagnets [1], and bulk magnetic doping [2,3]. Our experiments with chromium-doped topological insulator thin films detect these 1D chiral modes via the recently discovered quantum anomalous Hall effect. In addition, we demonstrate a magnetization-tilt driven crossover between a gapped quantum anomalous Hall insulator and a gapless, ferromagnetic topological insulator [3]. This crossover manifests itself in an electrically tunable, giant anisotropic magneto-resistance effect, which serves as a quantitative probe of the interplay between the 1D chiral modes and dissipative channels.   References: [1] A. Kandala et al., Appl. Phys. Lett. 103, 202409 (2013) [2] D. Zhang et al., Phys. Rev. B. 86, 2015127 (2012) [3] A. Kandala et al. arXiv:1503.03556