In this talk, I will discuss the rapidly developing field of nonreciprocal effects in superconducting transport, also known as the superconducting diode effect. The essence of this phenomenon lies in the asymmetry of a system’s properties when a supercurrent flows in opposite directions. Such an effect requires the simultaneous breaking of time-reversal and inversion symmetries. The underlying physical mechanisms can vary significantly, including effects of magnetic (and, more specifically, exchange) fields, spin-orbit interactions, and geometric asymmetry of the system. These effects can lead to nonreciprocal charge transport both in systems homogeneous along the current direction and in Josephson junctions.

BIOGRAPHY
Prof. Yakov Fominov holds two PhDs in Theoretical Physics — one from the Kapitza Institute (Russia, 2003) and another from the University of Twente (Netherlands, 2003) — as well as a Doctor of Physics and Mathematics degree from the Landau Institute (2019). Since 2005, he has been a permanent member of the Landau Institute, where he currently serves as Deputy Director. Since 2023, he has also headed the Chair for Problems in Theoretical Physics (Gor’kov Theory Group) at the Moscow Institute of Physics and Technology. His research focuses on the superconducting proximity effect in hybrid structures (including normal and ferromagnetic metals), the Josephson effect in mesoscopic junctions, odd-frequency superconductivity, and superconducting spin valves.

In this talk, I will discuss quantum states in Kagome lattices with the time reversal symmetry breaking. Both theory and recent experimental progress will be reviewed. A brief review of this type of states will be given for cuprates and Kagome lattice superconductors. We will discuss a specific model to show the existence of loop current states which break the time reversal symmetry as ground states. In particular, we will address the superconducting diode effect can be used to probe such quantum states.

BIOGRAPHY
Prof. Jiang-Ping Hu is currently a researcher and the Deputy Director of the Institute of Physics, Chinese Academy of Sciences. He received his BS from Peking University in 1994, MS from the Institute of Theoretical Physics of the Chinese Academy of Sciences in 1997 and PhD from Stanford University in 2002. His main research interests are theoretical condensed matter physics. He has made seminal contributions to topological physics, high-temperature superconductivity, and strongly correlated electron theory, with more than 280 publications and an H-index of 85. He was selected to be a Fellow of the American Physical Society in 2018, and was awarded the Zhou Peiyuan Prize for Physics in 2019, a New Stone Researcher in 2023.

Известно, что в магнитоупорядоченных средах, допускающих описание в терминах непрерывного векторного поля локальной намагниченности, могут существовать стабильные топологически нетривиальные магнитные состояния. Они соответствуют различным отображениям сферы на сферу. Целевая сфера -- множество точек на которых лежат концы векторов намагниченности (фиксированной длины), а исходная сфера -- пространство с наложенными периодическими граничными условиями на бесконечности. Одномерные (зависящие только от одной пространственной координаты) конфигурации соответствуют отображениям $S^1\to S^2$, двумерные (солитоны Белавина-Полякова) отображениям $S^2\to S^2$, а трёхмерные (магнитные хопфионы) отображениям $S^3\to S^2$. Все они распадаются на пронумерованные целыми числами (задающими количество солитонов в системе) гомотопические классы. Доклад посвящён вопросам стабильности, равновесия и (немного) динамики таких конфигураций, рассматриваемых с позиций теории микромагнетизма. Основные представленные результаты изложены в работах [1-5], но будут и более новые.

[1] K. L. Metlov, Simple analytical description of the cross-tie domain wall structure, Appl. Phys. Lett. 79(16) 2609 (2001).
[2] K. L. Metlov, Magnetization patterns in ferromagnetic nano-elements as functions of complex variable, Phys. Rev. Lett. 105(10) 107201(2010).
[3] K. L. Metlov, Equilibrium large vortex state in ferromagnetic disks, J. Appl. Phys. 113(22) 223905 (2013).
[4] K. L. Metlov, Vortex mechanics in planar nanomagnets, Phys. Rev. B. 88(1) 014427 (2013).
[5] K. L. Metlov, Two types of metastable hopfions in bulk magnets, Physica D 443, 133561 (2023).

We investigate analytically and numerically the statistical properties of the dynamics of rigid spherical particles with neutral buoyancy. The particles are placed in a turbulent flow with a strong shear component. As a simple model, we consider the shear flow of an axisymmetric vortex with turbulent fluctuations and calculate the particle distribution from the distance to the vortex center. We present quantitative results obtained within the framework of a point particle model with fluctuations that are correlated in time.

In 3D turbulent flows of a rotating system, where the Coriolis force prevails over the inertia in dynamics, formation of the columnar vortices takes place that is observed both experimentally [1] and numerically [2]. They are large-scale coherent flows that are homogeneous along the axis of rotation. Our work is about to build analytical model describing how axisymmetric vortex flow supports itself by absorbing inertial waves. We consider the following pumping mode: inertial waves reach the vortex from the periphery of system, where turbulence is excited. In the limits of short wavelengths and low viscosity we show that quasi-monochromatic wave that enters in the vortex transmits its energy and momentum only in the narrow vicinity of its critical layer [3] formed by an average shear flow. In our model we determine the Reynolds shear stress component averaged over inertial wave ensemble that sets the velocity profile of vortex [4]. [1] D.D. Tumachev, A.A. Levchenko, S.S. Vergeles, S.V. Filatov, Observation of a large stable anticyclone in rotating turbulence, PoF, 36(12), 126620 (2024). [2] Seshasayanan, K. & Alexakis, A. Condensates in rotating turbulent flows. JFM, 841, 434–462 (2018). [3] Haynes, P., 2015. Critical Layers. In: G. R. North et al., Encyclopedia of Atmospheric Sciences, 2nd edition, Vol 2. [4] I.V. Kolokolov, L.L. Ogorodnikov, and S.S. Vergeles, Structure of coherent columnar vortices in three-dimensional rotating turbulent flow, Phys. Rev. Fluids 5, 034604 (2020).