Quantum anomalous Hall effect, a member of quantum Hall trio featured with gapped bulk band dispersion and chiral edge propagating modes, is indebted to strong intrinsic magnetisation and large spin-orbit interaction. Depending upon the nature of exchange interaction and spin-orbit interaction, several theoretical models have been proposed for the realization of quantum anomalous Hall effect in various materials.
Symmetry analysis shows that all these various models can be described as special cases of a generalized low-energy effective Dirac Hamiltonian with a staggered exchange interaction and a mass term constraint by broken PT-symmetry to ensure non-zero Berry curvature. Furthermore, both the exchange interaction and the nontrivial bulk band gap can be optimized/tunned via gate electric field associated with breaking of mirror symmetries which leads to topological crystalline insulating phase otherwise. Such electric field induced optimization/tunability can be employed as promising platform for future low energy topological electronics devices based on quantum anomalous Hall insulators.
About the presenter
Muhammad Nadeem is a PhD student at University of Wollongong where he studies theory of 2D Chern/Z2 topological insulators with focus on Chern magnetism, role of various spin-orbit interactions, topological Skyrmion/Meron spin/pseudospin textures, and dissipationless transport.
Working with CIs Xiaolin Wang, Dimi Culcer, Alex Hamilton and Michael Fuhrer, his PhD project on exploring applications of 2D topological insulators for low-energy topological electronics and spintronics devices fits in FLEET’s Research theme 1, topological materials. He is also working on theoretical models for strongly correlated and unconventional topological phases, hosting quasiparticles with spin/pseudospin S > 1/2 and featured with multi-fold bulk band singularities, indebted to the broken Lorentz invariance in condensed matter systems.
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