I am a theorist in physics exploiting synergy between the theory of nonequilibrium processes and first principles methods for description of nanoscale materials and their properties.
After completion of my doctorate within European Commission Scholarship EMINENCE (2013-2015) I joined the Theory group of University of Warwick, where I work on development of new modelling capabilities for nano-confined phase change materials (with Dr David Quigley, in collaboration with experimental lead of Dr Jeremy Sloan).
Nanostructuring enables design of the novel materials with a range of properties enhanced in comparison to those of bulk materials. In this project, we focus on the materials that are scaled to a single dimension (1D) due to encapsulation within carbon nanotubes (CNTs).
Electron-phonon dynamics in a small diameter CNTs with encapsulated beryllium is characterised with a more effective phonon dissipation in comparison to pristine CNTs. This results in less electrons scattered by high-frequency atomic vibrations when voltage is applied, hence in increased electronic current. This work demonstrates the necessity of the coupled transport treatment for description of electron-phonon dynamics and offers a promising solution for future nanoelectronics.
Structure prediction. We have been successfully adapting ab initio random structure searching for prediction of the unique structures that materials develop in extreme confinement. E.g. a previously unreported 1D atomic helix of Te, and the smallest structures of phase change GeTe. These findings indicate a promising route towards minituarisation of non-volatile memory devices.
Electronic structure engineering. A general trend of a material structure evolution within CNTs of increasing diameter, i.e. from 1D chains towards a bulk-like structures of a nanowire, in SnTe, is accompanied with widening of the electronic band gap and increase of effective mass of electrons. This effect resulting in increase of Seebeck coefficient offers a new paradigm for overcoming the fundamental thermoelectric limitation, allowing for design of the novel thermoelectric materials with improved performance.
- "Encapsulated Nanowires: Boosting Electronic Transport in Carbon Nanotubes" A. Vasylenko, J. Wynn, P. Medeiros, A. J. Morris, J. Sloan, D. Quigley, Phys. Rev. B, 95, 121408(R), (2017), (see also arXiv:1611.04867).
"Single-Atom scale structural selectivity in Te nanowires encapsulated inisde ultra-narrow single-walled carbon nanotubes" P. V. C. Medeiros, S. R. Marks, J. M. Wynn, A. Vasylenko, Q. Ramasse, D. Quigley, J. Sloan, A. J. Morris, ACS Nano, 11, 6178–6185 (2017). DOI:10.1021/acsnano.7b02225. (see also arXiv:1701.04774).
- "Phase diagram of germanium telluride encapsulated in carbon nanotubes from first-principles searches" J. M. Wynn, P. V. C. Medeiros, A. Vasylenko, J. Sloan, D. Quigley, A. J. Morris, Phys. Rev. Mater., 1, 074002(R)/1-6 (2017). DOI: 10.1103/PhysRevMaterials.1.073001.
Dr Andrij Vasylenko
Department of Physics, University of Warwick, Coventry, CV4 7AL
Telephone: 44 (0) 24 7652 3413
E-Mail: a.vasylenko AT warwick.ac.uk