Magnetic Edge Doping of Chalcogenide-based Topological Insulators via Solvothermal Methods for Intrinsic Time Reversal Symmetry Breaking

Topological insulators (TIs) represent an intriguing class of materials that possess time symmetry- protected spin currents at their edge. Application of a magnetic field to such systems causes symmetry breaking and establishes a persistent charge current that circulates around the TI perimeter. Although external magnetic fields are typically discussed in the context of TI time reversal symmetry breaking, doping with magnetic materials might generate intrinsic fields that yield symmetry collapse while simultaneously allowing for donation of carriers that strengthen the charge current. Here, we present our work undertaken to produce chalcogenide-based TIs and subsequently achieve edge modulation doping with magnetic metals like iron or nickel. A versatile and straightforward solvothermal wet chemistry approach was used to synthesize high yields of bismuth telluride (Bi₂Te₃) platelets which have the potential for nanoparticle growth at reactive edge sites. Different concentrations of iron and nickel dopants were added to solutions of Bi₂Te₃ and the resultant materials were characterized to assess the extent of magnetic edge doping. A variety of techniques including electron microscopy (TEM, SEM, SAED), spectroscopy (XPS, EDS, XRD), Hall Effect measurements, and magnetic force microscopy were used to visualize nanoparticle formation, quantitatively assess material composition, confirm host material doping, and determine magnetic response. Preliminary results indicate that edge nanoparticle formation is taking place; experiments to optimize dopant growth, verify carrier injection from dopant to host and understand the influence of such dopants on the host material’s properties are ongoing. If magnetically doped chalcogenide TIs become a reality, they may play significant roles in quantum device and quantum information applications thanks to enhanced persistent charge currents that could maintain entanglement at relatively high temperatures.