Magneto-transport and X-ray Magnetic Circular Dichroism in Topological Insulator/Molecular Diode

The aim of this proposal is to study the electronic and magnetic states of Mn and Cu ions and C atoms on topological insulator (Bi2Se3 as TI)/molecular (C60 as n-type; MnPc and CuPc as the p-type) diode structures. We search for the origin of emergent transport properties such as increased Hall mobility, weak antilocalization and effective spin orbit coupling observed in magneto-transport and Raman measurements. For this purpose, we propose x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) at Mn, Cu-L and C-K absorption edges to disentangle the electronic and magnetic states of the TI-n-p and TI-p-n diode structures compared to control TI and molecular films. Using these measurements, we will demonstrate the modulation of charge transfer and/or interfacial hybridization in 2-D surface states modified with molecular diodes (either n-p or p-n). Overall, our results will pave the way for a new class of hybrid TI-organic structures where both the electronic and spin dependent properties can be tuned without destroying the two-dimensional physics.