2025 IEEE NTC TC10 Modeling and Simulation October Webinar

Date: 30 October 2025, 17:00

Time: 17:00 Berlin/Central European Time (16:00 UK, 12:00 New York, 09:00 California)

Speaker: Prof. Vladimir Fomin, Leibniz Institute for Solid State and Materials Research Dresden

Title: An Introduction to the Physics of Quantum Rings

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Abstract

An adequate modeling of the self-organized quantum rings is possible only on the basis of the modern characterization of those nanostructures. We discuss an atomic-scale analysis of the indium distribution of self-organized InGaAs quantum rings (QRs). The analysis of the shape, size and composition of self-organized InGaAs QRs at the atomic scale reveals that AFM only shows the material coming out of the QDs during the QR formation. The remaining QD material, as observed by Cross-Sectional Scanning Tunneling Microscopy (X-STM), shows an asymmetric indium-rich crater-like shape with a depression rather than an opening at the center and determines the observed ring-like electronic properties of QR structures. A theoretical model of the geometry and materials properties of the self-organized

QRs is developed on that basis and the magnetization is calculated as a function of the applied magnetic field. Although the real QR shape differs strongly from an idealized circular-symmetric open-ring structure, Aharonov-Bohm-type oscillations in the magnetization have been predicted to survive. They have been observed using the torsion magnetometry on InGaAs QRs. Large magnetic moments of QRs are shown to originate from dissipationless circulating currents in the ground state of an electron or hole in the QR.

Bio

Prof. Fomin is internationally recognized as an expert in nanophysics, covering a broad spectrum of topics such as the theory of 3D nanoarchitectures, topology- and geometry-driven effects in quantum rings, strain-induced self-rolled and direct-write micro- and nanoarchitectures, phase boundaries and vortex matter in micro- and nanoarchitectures and patterned superconductors. He has also made significant contributions to understanding the superconducting properties of metallic nanograins, phonons, vibrational excitations, polarons, electronic transport and optical effects in multilayer structures and superlattices, magnetopolarons and magneto-Raman scattering in monolayer Transition Metal Dichalcogenides. Additionally, his work extends to exploring topological states of light and spin-orbit coupling in microcavities, optical properties of quantum dots, thermoelectric properties of semiconductor nanostructures, quantum transport in sub-0.1 µm semiconductor devices, propulsion mechanisms of catalytic tubular micromotors, and theory of self-propelled micromotors for cleaning polluted water. His service as the Scientific Editor of the Encyclopedia of Condensed Matter Physics, 2nd Edition (Elsevier, 2024) and editor of three editions of Physics of Quantum Rings (Springer Nature, 2013, 2018 and 2025) further demonstrates his expertise and authority in the field. Prof. Fomin established a fundamental paradigm for superconductor 3D nanoarchitectures: a complex geometry leads to a strong inhomogeneity of the normal-to-the-surface magnetic field and to a non-trivial topology of screening supercurrents underlying novel physics of vortices and phase slips.