摘要

Electric field control of spin transport is crucial for many novel device concepts. In contrast to bulk materials, two-dimensional material are inherently thin and thus, can sufficiently minimize electric screening. They are also ideal to induce complementary properties by means of the proximity effect. For example, the combination of Rashba interaction, magnetic moments and electric field control of the density, is akin to dilute magnetic semiconductors. In a Dirac material this opens a route toward electric field control of magnetism and engineering topological magnetic states.
In the first part of my talk I will discuss efforts in inducing a large spin orbit coupling in graphene and spin transport studies in black phosphorus. Pristine graphene has negligible spin-orbit coupling (SOC). However, strong SOC can be induced, e.g. by hybridization with heavy metals. I will discuss experiments where this has been achieved with Au intercalated van der Waals heterostructures of graphene and hexagonal boron nitride [1]. The SOC of pristine black phosphorus (bP) is equally weak. Based on measurements in the non-local spin valves geometry, we show that the spin relaxation times can be as high as ~ 4ns with spin relaxation lengths exceeding 6 µm [2]. In principle this should make bP an equally exciting material platform for proximity effect studies in 2D. In the second part of my talk I will discuss the use of graphene and graphene like materials in magnetic hard disc drives. Here atomically thin anti-oxidation coatings are needed to further increase data storage density. However, existing non-2D coatings fail below 1 nm with respect to chemical inertness and thermal conductivity requirements. If time permits I will briefly also discuss other applications explored with industry, such as supercapacitors.

[1] O'Farrell, E. C. T., Tan, J. Y., Yeo, Y., Koon, G. K. W., Özyilmaz, B., Watanabe, K. and Taniguchi, T., Phys. Rev. Lett. 117, 076603 (2016)
[2] Avsar, A., Tan, J. Y., Kurpas, M., Gmitra, M., Watanabe K., Taniguchi, T., Fabian, J. and Özyilmaz, B., Nature Physics (2017).

报告人简介

Barbaros Özyilmaz
Deputy Director
Centre of Advanced 2D Materials, National University of Singapore (NUS), Singapore.

History
July 2016 till present: Deputy Director (Translation)
Centre of Advanced 2D Materials, National University of Singapore (NUS), Singapore.

October 2014 till present: Head of Graphene Research
Centre of Advanced 2D Materials, National University of Singapore (NUS), Singapore.

September 2015 till present: Professor
Department of Materials Science and Engineering

September 2013 till present: Professor
Department of Physics, National University of Singapore (NUS), Singapore.

Graduate degree: Ph.D. in Physics, New York University (NYU), NY, USA. January 2005.

Award
IPS World Scientific Award 2013, Institute of Physics, Singapore.
Young Research Award (YRA) 2013, National University of Singapore (NUS), Singapore.
Young Scientist Award 2012, Science Faculty, National University of Singapore (NUS), Singapore.
Young Investigator Award (YIA) 2010, National University of Singapore (NUS), Singapore.

Host: Jinfeng Jia