EventDr. Ahmet Avşar

Spin transport in novel two-dimensional materials and van der Waals heterostructures

Electron spin is an important degree of freedom which can complement charge in information storage and logic devices. With respect to the material selection for spintronics, two-dimensional (2D) materials and their van der Waals heterostructures offer new opportunities that are unfeasible in bulk materials. In this talk, I will first discuss basics of graphene spintronics and our attempts for solving its major issues. Our advancements include spin lifetimes enhancement of graphene spin valves, nondestructive optical spin injection in order to eliminate contact induced spin dephasing effects, realization of spin switch effect and enhancement of its very weak spin orbit coupling strength in order to create opportunities for the manipulation of spin current. These have been achieved by creating artificial interfaces with other 2D crystals such as boron nitride (h-BN) and transition metal dichalcogenides (TMDCs). Then, I will discuss our spin transport measurements performed in 2D semiconductor materials. I will introduce ultra-thin, semiconducting black phosphorus as a promising material for possible spintronics applications requiring rectification and amplification actions (See figure). I will demonstrate that its spin transport properties can be manipulated in a transistor-like manner by just controlling the electric field even at room temperature thanks to its semiconducting nature. I will also discuss our recent quantum transport and optic measurements probing the spin/valley dynamics at the conduction and valance bands of semiconducting monolayer TMDCs. Finally I will provide my perspective about 2D spintronics.


Figure:  Top panel represents the device schematic of black phosphorus (BP) based spin valve device. Bottom panel shows electronic spin transport and spin precession measurements in ultra-thin BP spin valve device. From A. Avsar et al., Nat. Phys., 13, 888-893 (2017).

About The Speaker


Dr Ahmet Avsar is an experimental condensed matter physicist specializing in the emerging fields of spintronics and two-dimensional crystals-based nanotechnology. Specifically, he studies the electron and spin transport in lithographically patterned mesoscopic devices. These devices utilize van der Waals bonded two-dimensional crystals such as graphene, black phosphorus, transition metal dichalcogenides and boron nitride. He obtained PhD degree from Physics Department of National University of Singapore and he is currently a research fellow at Ecole Polytechnique Federale de Lausanne (EPFL), Switzerland. He is a recipient of 2016- EPFL Fellows fellowship award co-fund by Marie Skladowska-Curie.