Defects in Black Phosphorus: Screening, Doping, and Magnetism Friday, March 1, 2019

Defects in Black Phosphorus: Screening, Doping, and Magnetism
Friday, March 1, 2019
11:00 – 12:00 pm
Singh Center for Nanotechnology, Conference Room 313

Brian Kiraly, Ph.D.

Radboud University, Institute for Molecules and Materials, The Netherlands

Black phosphorus (BP) has recently gained substantial momentum within the fields of physics, electronics and optoelectronics because of its layer-dependent band gap spanning the visible spectrum, high carrier mobility, and field-tunable band topology. While black phosphorus devices gain sophistication and performance at remarkable speeds, the atomic scale properties remain largely unexplored. In this talk, I will discuss our recent studies of both intrinsic and extrinsic defects on BP at the atomic scale via scanning tunneling microscopy. Using atomic scale probes, we have been able to classify, characterize, and quantify the primary native defects in BP, namely P vacancies [1]. We have further shown that such vacancies host electronic states near the valence band edge, acting a p-type dopants and serve as scattering centers for free carriers. The interactions and arrangements of alkali metal dopants on the surface of BP have revealed a complex distance dependent electrostatic screening mediated by strongly confined 2D states at the BP surface. Finally, I will discuss the peculiar case of single cobalt atom (extrinsic defect) on the surface of black phosphorus [2]. Screening from the black phosphorus enables these magnetic atoms to stabilize multiple orbital configurations (3d8 and 3d9) allowing us to demonstrate a proof-of-concept single atom magnetic memory.

[1] Kiraly Nano Letters 17, 3607 (2017).

[2] Kiraly et. al. Nature Commun. 9, 3904 (2018).