Harvard Quantum Initiative Special Seminar
Wednesday, February 13
3:00 PM
Jefferson 250
Maryam Salehi (Rutgers)
The art of defect engineering in epitaxially-grown topological insulators and topological
quantum effects
Topological insulators (TIs) are a class of electronic materials which are predicted to be
insulating in the bulk and conducting on the boundary surfaces. Since their discovery,
material defects have remained as the major obstacle to achieving bulk-insulating TIs.
Particularly, efforts to obtain TI thin films with suppressed bulk defects and dominant
surface transport have always led to introduction of additional surface defects, thereby
shifting the Fermi level away from the Dirac point and deep into the conduction (valence)
band. The high defect densities obscure the topological surface states (TSS) and make it
impossible to access the Dirac point which is crucial for probing the physics of TSS and
the zeroth Landau level as well as fabricating TI-based devices. In this talk, I will
discuss how defects have been affecting the properties of TIs and show how suppressing
defects in V-VI TIs through a proper interface engineering led to achieving unprecedented
low carrier density TI films which revealed the heretofore inaccessible topological
quantum aspects of TIs, such as TSS-originated quantum Hall effect, quantized Faraday and
Kerr rotation, finite-size topological phase transition, etc.
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