Vortex patterns in Intertype Superconductivity Regime in thin and nanowire superconductors
On January 22, a joint seminar of the School of Electronic Engineering and the Quantum Nanoelectronics Laboratory was held in MIEM HSE building. MIEM postdoc Wilmer Yesid Cordoba Camacho gave a talk "Vortex patterns in Intertype Superconductivity Regime in thin and nanowire superconductors".
Based on the Ginzburg-Landau theory, superconducting materials are classified as ideally diamagnetic type-I or type-II, where the magnetic field penetrates the superconducting condensate as a regular lattice of Abrikosov single-quantum vortices, depending on the Ginzburg-Landau parameter k. However, this simple classification applies only for materials deep in type-I (k< 1/√2) or in deep type-II (k< 1/√2). Superconducting materials with k in the vicinity of k≈ 1/√2 (the Bogomolnyi point) reveals non-standard properties that cannot be described within the conventional type-I/type-II dichotomy. These materials are broadly referred as intertype (IT) superconductors. The existence of the IT superconductivity is a general property of the BCS pairing mechanism and is related to the infinite degeneracy of the Bogomolnyi point. By lowering the temperature or introducing impurities and/or defects this degeneracy is removed, leading to many unconventional properties of the superconducting mixed state. The magnetic field in this case can penetrate in the form of "giant vortexes", "drops", "lamellas" and other unusual structures. The speaker presented the results of modeling the vortex structures of IT superconductivity. In particular, it was shown that the superconducting state in thin films (nanowires) undergoes complex transformations depending on the thickness (diameter) of the structure. The formation of vortices has a significant impact on the magnetic properties of superconductors and, therefore, on their technological applications.
Wilmer Yesid Cordoba Camacho received his Ph.D. in 2018 from the Physics Department of the Federal University of Pernambuco (Recife, Brazil) [https://www.ufpe.br/]. In October 2018, he became postdoc in the Higher School of Economics. Wilmer’s supervisor is Associate Professor of the School of Electronic Engineering A.S. Vasenko.