Anomalous Josephson Hall effect charge and transverse spin currents in superconductor/ferromagnetic insulator/superconductor junctions

Interfacial spin-orbit coupling in Josephson junctions offers an intriguing way to combine anomalous Hall and Josephson physics in a single device. We study theoretically how the superposition of both effects impacts superconductor/ferromagnetic insulator/superconductor junctions' transport properties. Transverse momentum-dependent skew tunneling of Cooper pairs through the spin-active ferromagnetic insulator interface creates sizable transverse Hall supercurrents, to which we refer as anomalous Josephson Hall effect currents. We generalize the Furusaki-Tsukada formula, which got initially established to quantify usual (tunneling) Josephson current flows, to evaluate the transverse current components and demonstrate that their amplitudes are widely adjustable by means of the spin-orbit coupling strengths or the superconducting phase difference across the junction. As a clear spectroscopic fingerprint of Josephson junctions, well-localized subgap bound states form around the interface. By analyzing the spectral properties of these states, we unravel an unambiguous correlation between spin-orbit coupling-induced asymmetries in their energies and the transverse current response, founding the currents' microscopic origin. Moreover, skew tunneling simultaneously acts like a transverse spin filter for spin-triplet Cooper pairs and complements the discussed charge current phenomena by their spin current counterparts. The junctions' universal spin-charge current cross ratios provide valuable possibilities to experimentally detect and characterize interfacial spin-orbit coupling

Microscopic study of the Josephson supercurrent diode effect in 2DEG-based Josephson junctions

Superconducting systems that simultaneously lack space-inversion and time-reversal symmetries have recently been the subject of a flurry of experimental and theoretical research activities. Their ability to carry supercurrents with magnitudes depending on the polarity (current direction) - termed supercurrent diode effect - might be practically exploited to design dissipationless counterparts of contemporary semiconductor-based diodes. Magnetic Josephson junctions realized in the two-dimensional electron gas (2DEG) within a narrow quantum well through proximity to conventional superconductors perhaps belong to the most striking and versatile platforms for such supercurrent rectifiers. Starting from the Bogoliubov-de Gennes approach, we provide a minimal theoretical model to explore the impact of the spin-orbit coupling and magnetic exchange inside the 2DEG on the Andreev bound states and Josephson current-phase relations. Assuming realistic junction parameters, we evaluate the polarity-dependent critical currents to quantify the efficiency of these Josephson junctions as supercurrent diodes, and discuss the tunability of the Josephson supercurrent diode effect in terms of spin-orbit coupling, magnetic exchange, and transparency of the nonsuperconducting weak link. Furthermore, we demonstrate that the junctions might undergo current-reversing $0$-$\pi$-like phase transitions at large enough magnetic exchange, which appear as sharp peaks followed by a sudden suppression in the supercurrent-diode-effect efficiency. The characteristics of the Josephson supercurrent diode effect obtained from our model convincingly reproduce many unique features observed in recent experiments, validating its robustness and suitability for further studies.Comment: 11+2 pages, 9 figure

Theoretical investigations of charge and spin transport through superconducting tunnel junctions

Superconducting tunnel junctions exhibit not only extraordinary physical phenomena, but simultaneously provide unique possibilities to generate and control spin-polarized supercurrents as the essential ingredients for numerous modern technologies, especially for recent quantum-computing concepts. Bringing superconductivity together with its nominally antagonistic ferromagnetic phase gives rise to particularly rich physics that might soon facilitate additional functionalities in spintronics applications. Prominent examples cover magnetic Josephson junctions, in which the competing superconducting and ferromagnetic properties can add intrinsic π-phase shifts to the junctions’ characteristic sinusoidal current-phase relations and thereby even reverse the directions of the Josephson currents. Implementing a reliable control knob between these π- and the junctions’ initial 0-states might mark the first great step towards the realization of quantum bits in prospective computers. The interplay between superconductivity and ferromagnetism gets most intriguing in tunnel regions that furthermore host (interfacial) spin-orbit couplings. The resulting competition between the ferromagnetic exchange and the spin-orbit interactions has unambiguous signatures in spectroscopy and electrical transport – mostly due to long-range superconducting proximity effects that induce triplet superconducting correlations even in strongly spin-polarized ferromagnets –, and is moreover expected to support topological superconductivity and emergent Majorana states. In this dissertation, we will perform systematic and comprehensive microscopic model calculations for various superconducting magnetic tunnel geometries, allowing us to theoretically study the ramifications of combining superconductivity with magnetic exchange and spin-orbit couplings in real devices. The work’s main directions cover conductance simulations of ferromagnet/superconductor multilayer junctions, bound state and Josephson current analyses of different classes of magnetic Josephson contacts, and finally a profound discussion of transverse Hall supercurrent phenomena. Paying special attention on unraveling clear fingerprints of the investigated effects and practical feasibility, our results might boost subsequent experimental efforts and contribute to gain more insight into the surprising physics of superconducting magnetic tunnel configurations

On the uniqueness of (p,h)(p,h)-gonal automorphisms of Riemann surfaces

Let $X$ be a compact Riemann surface of genus $g\geq 2$. A cyclic subgroup of prime order $p$ of $Aut(X)$ is called properly $(p,h)$-gonal if it has a fixed point and the quotient surface has genus $h$. We show that if $p>6h+6$, then a properly $(p,h)$-gonal subgroup of $Aut(X)$ is unique. We also discuss some related results.Comment: final version, 9 pages, minor improvements, added 2 reference

Sex Differences in Speed and Acceleration Metrics in Soccer A Case of NCAA, Division III Student-Athletes

According to American College of Sports Medicine (ACSM) reports, wearable technology is the number one fitness trend for 2020 in the US. Division III (DIII) schools are the biggest participant in the National Collegiate Athletic Association (NCAA). In terms of number of student-athletes, soccer is the second most popular sport in NCAA. Duration of high speed and number of accelerations/decelerations have been identified as correlates of injuries, such as anterior cruciate ligament (ACL) injury, especially in female athletes. PURPOSE: To examine whether there are sex difference in the relationship of speed and acceleration metrics in collegiate soccer. METHODS: All 56 players of the same SUNYAC men’s and women’s soccer teams agreed to participate (Mage =19.42, SD=1.09). Data were collected usingthe Titan 1+ GPS sensor. In total, 200 assessments took place in pre-season and in-season. Speed zone was defined as the duration the athlete spent traveling ≥ 6m/s and was reported in minutes. Acceleration/deceleration was defined as the number of peak accelerations (≥ 3m/s2)/decelerations (≤ 3m/s2) experienced by the athlete and was reported in counts. The analysis consisted of Pearson correlations and a chi-square test by gender in R. RESULTS: The correlation matrices of speed zone and both acceleration and deceleration between males and females were statistically different: (x2(15) = 10.54, p \u3c .01). Specifically, there was a difference in correlations between speed zone and acceleration (rm = .61, rf = .86, Z = -2.15, p = .032) and between speed zone and deceleration (rm = .47, rf = .79, Z = -2.06, p = .039). CONCLUSION: Our findings indicate that our female participants experienced a significantly higher number of accelerations/decelerations when in high speed. Combining these results with the already known risk factors of the etiology of lower-body injuries in female athletes (e.g., anatomy, hormones) adds one more reason why practitioners should focus on a comprehensive neuromuscular and proprioceptive training program (e.g., accelerated rounded turns, deceleration with multi-step stop) to decrease lower-body (e.g., ACL) injuries in female soccer student-athletes. Future studies should explore additional external metrics (e.g., impact metrics), include internal metrics (e.g., sRPE), investigate differences between practice and game-day data, and collect information from larger and Division I/II samples. Possible limitations include convenience sample

Gain in Three-Dimensional Metamaterials utilizing Semiconductor Quantum Structures

We demonstrate gain in a three-dimensional metal/semiconductor metamaterial by the integration of optically active semiconductor quantum structures. The rolling-up of a metallic structure on top of strained semiconductor layers containing a quantum well allows us to achieve a three-dimensional superlattice consisting of alternating layers of lossy metallic and amplifying gain material. We show that the transmission through the superlattice can be enhanced by exciting the quantum well optically under both pulsed or continuous wave excitation. This points out that our structures can be used as a starting point for arbitrary three-dimensional metamaterials including gain

Herding, contrarianism and delay in financial market trading

Herding and contrarian behaviour are often-cited features of real-world financial markets. Theoretical models of continuous trading that study herding and contrarianism, however, usually do not allow traders to choose when to trade or to trade more than once. We present a large-scale experiment to explore these features within a tightly controlled laboratory environment. Herding and contrarianism are more pronounced than in comparable studies that do not allow traders to time their decisions. Traders with extreme information tend to trade earliest, followed by those with information conducive to contrarianism, while those with the theoretical potential to herd delay the most. A sizeable fraction of trades is clustered in time

The model of local axon homeostasis - Explaining the role and regulation of microtubule bundles in axon maintenance and pathology

Axons are the slender, cable-like, up to meter-long projections of neurons that electrically wire our brains and bodies. In spite of their challenging morphology, they usually need to be maintained for an organism's lifetime. This makes them key lesion sites in pathological processes of ageing, injury and neurodegeneration. The morphology and physiology of axons crucially depends on the parallel bundles of microtubules (MTs), running all along to serve as their structural backbones and highways for life-sustaining cargo transport and organelle dynamics. Understanding how these bundles are formed and then maintained will provide important explanations for axon biology and pathology. Currently, much is known about MTs and the proteins that bind and regulate them, but very little about how these factors functionally integrate to regulate axon biology. As an attempt to bridge between molecular mechanisms and their cellular relevance, we explain here the model of local axon homeostasis, based on our own experiments in Drosophila and published data primarily from vertebrates/mammals as well as C. elegans. The model proposes that (1) the physical forces imposed by motor protein-driven transport and dynamics in the confined axonal space, are a life-sustaining necessity, but pose a strong bias for MT bundles to become disorganised. (2) To counterbalance this risk, MT-binding and -regulating proteins of different classes work together to maintain and protect MT bundles as necessary transport highways. Loss of balance between these two fundamental processes can explain the development of axonopathies, in particular those linking to MT-regulating proteins, motors and transport defects. With this perspective in mind, we hope that more researchers incorporate MTs into their work, thus enhancing our chances of deciphering the complex regulatory networks that underpin axon biology and pathology

Structural Parameters of Seven SMC Intermediate-Age and Old Star Clusters

We present structural parameters for the seven intermediate-age and old star clusters NGC121, Lindsay 1, Kron 3, NGC339, NGC416, Lindsay 38, and NGC419 in the Small Magellanic Cloud. We fit King profiles and Elson, Fall, and Freeman profiles to both surface-brightness and star count data taken with the Advanced Camera for Surveys aboard the Hubble Space Telescope. Clusters older than 1 Gyr show a spread in cluster core radii that increases with age, while the youngest clusters have relatively compact cores. No evidence for post core collapse clusters was found. We find no correlation between core radius and distance from the SMC center, although consistent with other studies of dwarf galaxies, some relatively old and massive clusters have low densities. The oldest SMC star cluster, the only globular NGC121, is the most elliptical object of the studied clusters. No correlation is seen between ellipticity and distance from the SMC center. The structures of these massive intermediate-age (1-8 Gyr) SMC star clusters thus appear to primarily result from internal evolutionary processes.Comment: 16 pages, 13 figure