Magnetic Topological Materials - K. Manna

Design of energy saving dissipationless electronics is one of the major quests of modern science. Magnetic Weyl semimetals are the new class of materials that serve as an ideal platform to design super-fast electronic devises using its exotic topological properties and use of magnetic spins for the spintronic applications involving quantum computing, hand disk drive, data storage etc. One of the most challenging phenomena here is to obtain the room temperature “Quantized Anomalous Hall Effect”, where dissipationless chiral edge states appear as quantum Hall effect in absence of a magnetic field. The goal deserves discovery of new promising materials with the combined input of theoretical guidance, chemical engineering and excellent experimental skill. In this group, we grow high quality single crystals and perform the magnetic as-well-as electrical transport characterizations to understand the interplay of crystal symmetry and magnetic structure in topological materials. This enables us to realize various exotic topological phases of matter through the Berry curvature design. Berry curvature is the equivalent of magnetic field in the momentum space that illustrates electronic entanglement between the valence and conduction bands in topological band structure.

In the electrical transport experiment, we measure the anomalous Hall conductivity, which is the integration of Berry curvature for all the states up to fermi level. So as we tune the details of the topological bands via external perturbations (magnetic field, pressure etc.), the Berry curvature distribution changes and one can realize various exotic phenomena like chiral magnetic effect or gravitational anomaly, large topological Hall effect etc. In the magnetic Weyl semimetals, the time-reversal symmetry is naturally broken and by the combined effect of high anomalous Hall angle with arrested perpendicular magnetization the quantized anomalous Hall effect can be obtained in the 2-D confinement at higher temperature. The aim of this group is to discover new magnetic topological materials with exotic quantum properties via magnetic and electrical transport characterizations.

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