IMX Seminar Series - Superlative spin transport in two-dimensional black phosphorus.

Exploitation of the intrinsic spin of an electron, spintronics, facilitates the development of multifunctional and novel devices which could play an important role in the Beyond-CMOS era. Two-dimensional (2D) crystals and their van der Waals heterostructures are particularly promising for spintronics device applications due to their unique properties, including strong responses to field effect gating and proximity interactions, which may enable new functionalities that are not possible with conventional bulk materials [1].
Black phosphorus is a particularly promising 2D semiconducting material for spintronics research due to its high charge mobilities, low atomic mass, and puckered crystalline structure, which are expected to lead to anisotropic spin transport with nanosecond spin-lifetimes. In this seminar, I will introduce ultra-thin BP as a unique platform for studying rich spin-dependent physics. Firstly, I will show that BP supports all electrical spin injection, transport, precession and detection up to room temperature [2]. Then, I will present our recent findings on the impact of the unique crystal structure of BP on its spin dynamics, revealing strong anisotropic spin transport along three orthogonal axes [3-a]. Finally, I will show that we have achieved the longest spin lifetimes and highest spin signals ever measured in a spin channel material by optimising the charge carrier type and concentration in BP using electrostatic gating and proximity interactions [3-b]. The exceptional spin transport and strong spin-lifetime anisotropy we observe in BP add to the growing body of evidence for the potential of 2D materials in functional spin-based device applications.
[1] A. Avsar et al., Rev. Mod. Phys. 92, 021003 (2020), J. F. Sierra et al., Nat. Nano., 16, 856-868 (2021)
[2] A. Avsar et al., Nat. Phys. 13, 888-894 (2017)
[3] a-) L. Cording et al., submitted (2022), b-) J. Liu et al., submitted (2022).
Bio: Dr Ahmet Avsar is an Assistant Professor and NRF Fellow in the Department of Material Science and Engineering at the National University of Singapore (NUS). Prior to joining NUS, he was an Assistant Professor of Physics at Newcastle University (UK). He worked as a postdoctoral researcher (EPFL Fellow) at the Ecole Polytechnique Federale de Lausanne between 2016 and 2020 after completing his PhD in Physics at NUS.
As an experimental condensed matter physicist specialized in two-dimensional (2D) materials, Ahmet Avsar is interested in exploitation of the multiple quantum degrees of freedom (spin, pseudospin and valley) available to 2D materials in the ultimate atomically thin limit for applications in energy-efficient information technologies.