Physics Colloquium: Yohannes Abate, "Probing interactions at the nanoscale"

Dates
Wed, Feb 02, 2022 - 04:00 PM 鈥 Wed, Feb 02, 2022 - 05:00 PM
Admission Fee
free
Event Address
By Zoom. Please contact Prof. Sriram Ganeshan for details: sganeshan@ccny.cuny.edu
Event Details

Yohannes Abate

The Susan Dasher and Charles Dasher MD Professor of Physics

Department of Physics and Astronomy

University of Georgia. Athens, GA

 

Abstract 

 

Interactions at the nanometer length scale in hard and soft condensed matter give rise to intriguing phases in correlated electron materials, lead to the design of exotic metamaterials, and offer enormous opportunities for the development of novel optoelectronic devices. In this talk, I will give examples of high-resolution probing of nanoscale physical phenomena and interactions in quantum materials specifically correlated oxides and van der Waals (vdW) crystals. Correlated oxides provide exciting opportunities to reconfigure polaritonic devices at the nanoscale, due to their highly tunable local optical and electronic properties [1,4-6]. I will introduce a hybrid polaritonic-oxide heterostructure platform consisting of vdW crystals, such as hexagonal boron nitride or alpha-phase molybdenum trioxide, transferred on nanoscale oxygen vacancy patterns on the surface of correlated perovskite oxide SmNiO3 (SNO)[1]. Hydrogenation and temperature modulation allow spatially localized conductivity modulation of SNO nanoscale patterns, enabling robust real-time modulation and nanoscale reconfiguration of hyperbolic polaritons. We have developed a simulational methodology to calculate the nanoscale modulation of the dielectric response of SNO with respect to differing levels of hydrogenation and oxygen vacancy formation using a combination of Langevin dynamics and Metropolis Monte Carlo methods. Interaction of vdW crystals with oxygen and water in ambient environment leads to enhanced chemical reactivity of their extraordinarily high surface areas. Using a combination of hyperspectral tip-enhanced photoluminescence, Raman, and near-field nanoscopy I will present recent imaging and spectroscopy results that reveal exotic interface effects and oxidized species during photodegradation of 2D in-plane MoS2鈥揥S2 heterostructures with nanoscale alloyed interfaces and thin flakes of allotropes of phosphorus (black and violet phosphorus)[2.3]. The 2D alloy interface coupled with intrinsic strain causes spatial inhomogeneity of the oxidation and emission of the various excitonic species, providing localized potential wells at corner interfaces for various charge carriers and enabling localized emission with enhanced stability.

 

1. N. A. Aghamiri, G. Hu, A. Fali, Z. Zhang, J. Li, S. Balendhran, S. Walia, S. Sriram, J. Edgar, S. Ramanathan, A. Alu, and Y. Abate, 鈥淩econfigurable Hyperbolic Polaritonics with Correlated Oxide

Metasurfaces鈥 Nature Comm. (Under Review), DOI:10.21203/rs.3.rs-947391/v1

 

2. A. Fali, M. Snure, and Y. Abate, 鈥淰iolet phosphorus surface chemical degradation in comparison to black phosphorus鈥 Appl. Phys. Lett. (Editor鈥檚 Pick), 118, 163105 (2021) DOI: 10.1063/5.0045090

 

3. A. Fali, T. Zhang, J. Terry, E. Kahn, K. Fujisawa, S. Koirala, Y. Ghafouri, W. Song, L. Yang, M. Terrones, Y. Abate, Y. Abate, 鈥