| Description |
Three-dimensional (3D) topological insulators (TI) are typically narrow band gap semiconductors with in-gap surface states that are characterized by a Dirac dispersion and helical spin texture. Magnetic perturbations can further gap these states at the Dirac point, creating a rich playground for exotic quantum phenomena, including a zero-field quantum Hall effect. In this talk, I’ll present two different schemes for probing these effects in electrical transport devices – interfacing with insulating ferromagnets, as well as magnetic doping. In particular, the experiments with Chromium (Cr) doped TI thin films reveal a field-tilt driven crossover between a gapped quantum anomalous Hall insulator and a gapless, ferromagnetic TI. This crossover manifests itself in a novel, gate-tunable, giant anisotropic magneto-resistance effect.
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