Search

Noise and current measurements are key tools for studying mesoscopic systems, revealing insights beyond conductance alone. For instance, noise measurements show that transport carriers in conventional superconductors have charge 2e. The noise power also depends on junction type, distinguishing different transport processes. Existing theories focus primarily on zero temperature shot noise in tunnel junctions with conventional superconductors, where transport is carried by quasiparticles and Cooper pairs. Here we develop a full counting statistics theory for unconventional superconductor / normal metal junctions of different types, incorporating the effect of thermal noise on the differential Fano factor, the ratio of differential noise power and conductance. In these junctions there is a third type of transport carrier, surface Andreev bound states. Our study reveals that junctions with dispersionless surface Andreev bound states exhibit negative differential Fano factor at finite temperatures. In contrast, in the presence of dispersive surface Andreev bound states, the noise power always increases with voltage, but there are local minima in the differential noise at those voltages corresponding to the extrema of the surface Andreev bound state spectrum. For normal metals and conventional superconductors the voltage dependence of the differential Fano factor is similar in all types of junctions, including tunnel junctions and diffusive barriers. However, significant differences arise with unconventional superconductors, making distinct junction types valuable tools for identifying pairing symmetries. Our results also highlight the importance of finite temperature effects in noise power measurements for potential unconventional superconductors, offering new means to determine pairing symmetries in topological superconductors., Comment: 80 pages, 43 figures

We present a method for detecting the chirality $\chi$ of a ($d_{zx}+i \chi d_{yz}$)-wave superconductor through the analysis of the local density of states (LDOS) at the vortex core. Employing the quasiclassical Eilenberger theory, we examine the LDOS in a semi-infinite superconductor with a quantum vortex penetrating the surface perpendicularly. We show that $\mathrm{sgn}[\chi]$ changes completely the LDOS at the core-surface intersection. Remarkably, the difference between LDOS for the $\chi = 1$ and $\chi = -1$ states becomes more prominent when the surface is dirtier, meaning that one does not need to pay close attention to the surface quality of the sample. The difference between these two states arises from the symmetry of the subdominant Cooper pairs induced at the core-surface intersection: whether the subdominant $s$-wave Cooper pairs are present or not. Due to the unique nature of this phenomenon in the ($d_{zx}+i \chi d_{yz}$)-wave superconductor, one can potentially demonstrate the realization of the ($d_{zx}+i \chi d_{yz}$)-wave superconductivity and determine its chirality by, for instance, through scanning tunnel spectroscopy experiments., Comment: 9 pages, 7 figures, 1 table

We study the spontaneous chiral surface current circulating in a three-dimensional disk of a chiral superconductor (SC) utilizing the quasiclassical Eilenberger theory. We obtain spatial profiles of the chiral current for both a ($d_{zx} + i d_{yz}$)-wave and a ($p_{x} + i p_{y}$)-wave SCs (where the top and bottom surfaces of the disk are perpendicular to the $z$-axis). Whereas the chiral current for a ($p_{x} + i p_{y}$)-wave SC does not depend on $z$, a reversal of the chiral current takes place at the top and bottom surfaces in the case of a ($d_{zx} + i d_{yz}$)-wave SC. In this latter case, flat-band Andreev bound states appear at the top and bottom surfaces in addition to the chiral surface states at the lateral surface. The chiral current reversal is explained in terms of hybridization between the two types of Andreev bound states. As a result, the magnetic field around the disk differs drastically between the two cases., Comment: 6 pages, 5 figures, Supplemental Materials

Superconducting proximity junctions based on topological insulators are widely believed to harbor Majorana-like bound states. The latter serves as a paradigm non-local topological quantum computation protocols. Nowadays, a search for topological phases in different materials, perspective for a realization of topological qubits, is one of the central efforts in quantum physics. It is motivated, in particular, by recent observation of anomalous ac Josephson effect, which being a signature of Majorana physics. Its manifestations, such as a fractional Josephson frequency and the absence of the first (or several odd in more rare cases), Shapiro steps, were reported for different materials. Here we study Shapiro steps in Nb/Bi2Te2.3Se0.7/Nb junctions, based on ultrasmall single crystals of a 3D topological insulator synthesized by a physical vapor deposition (PVD) technique. We present evidence that our junctions are ballistic. When subjected to microwave radiation, the junctions exhibit Shapiro steps, but the first step is missing. Typically it is assumed that the missing first step (MFS) effect cannot be observed in the presence of quasiparticle poisoning due to suppression of the 4{\pi}-periodic component. Our findings within the context of the RSJ-model of Josephson junction dynamics show that such behaviour of samples corresponds to a specific condition, requiring a minimum of 5% of the 4{\pi}-component for disappearance of the first Shapiro step., Comment: Keywords: Shapiro step missing, Topological insulator, Superconductivity, Ballistic transport, 4{\pi}-periodic component

The influence of Rashba spin-orbit coupling (SOC) on superconducting correlations in thin-film superconductor/antiferromagnet (S/AF) structures with compensated interfaces is studied. A unique effect of anisotropic enhancement of proximity-induced triplet correlations by the SOC is predicted. It manifests itself in the anisotropy of the superconducting critical temperature Tc with respect to orientation of the Neel vector relative to the S/AF interface, which is opposite to the behaviour of Tc in superconductor/ferromagnet structures. We show that the anisotropy is controlled by the chemical potential of the superconductor and, therefore, can be adjusted in (quasi)2D structures.

In non-centrosymmetric superconductors the pair potential has both even-parity singlet and odd-parity triplet components. If time-reversal symmetry is broken, the superconducting phase of these components is not the same, for example in anapole superconductors. In this paper it is shown that breaking time-reversal symmetry by a phase difference between the two components significantly alters both the density of states and the conductance in s+helical p-wave superconductors. The density of states and conductance in s+chiral p-wave superconductors are less influenced by adding a phase difference because time reversal symmetry is already broken in the s+p-wave superconductor. The Tanaka-Nazarov boundary conditions are extended to 3D superconductors, allowing to investigate a greater variety of superconductors, such as B-W superconductors, in which the direction of the d-vector is parallel to the direction of momentum. The results are important for the determination of pair potentials in potentially time-reversal symmetry broken non-centrosymmetric superconductors., Comment: 13 pages, 18 figures

The robustness of the chiral surface current of chiral superconductors against surface roughness is studied utilizing the quasiclassical Eilenberger theory. We consider the general chiral superconductors where the pair potential is given by the spherical harmonics $Y_l^m$ such that $(l,m)=(1, \pm1)$ state corresponds to an ($p_x \pm ip_y$)-wave superconductor. The self-consistent calculations demonstrate that the robustness of the chiral current is determined by whether subdominant $s$-wave Cooper pairs are induced by disorder. The induced $s$-wave pairs act as an effective pair potential. As a result, the spontaneous chiral current of ($p_x+ip_y$)- and ($d_{x^2-y^2}+id_{xy}$)-wave superconductors are robust against the roughness because the subdominant $s$-wave Cooper pairs are present., Comment: 10 pages, 9 figures

We study theoretically the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states appearing locally in a superconducting thin film with a small circular magnetic cluster. The pair potential, the pairing correlations, the free-energy density, and the quasiparticle density of states are calculated for several cluster sizes and the exchange potentials by solving the Eilenberger equation in two dimensions. The number of nodes in the pair potential increases with increasing the exchange potential and cluster size. The local FFLO states are stabilized by the superconducting condensate away from the magnetic cluster even though the free-energy density beneath the ferromagnet exceeds locally the normal-state value. The analysis of the pairing-correlation functions shows that the spatial variation of the spin-singlet $s$-wave pair potential generates $p$-wave Cooper pairs, and that odd-frequency Cooper pairs govern the inhomogeneous subgap spectra in the local density of states. We also discuss a way of detecting the local FFLO states based on the calculated quasiparticle density of states., Comment: 9 pages, 6 figures

Recently the superconducting diode effect (SDE) has attracted a lot of attention due to new possibilities in the field of superconducting electronics. One of the possible realizations of the SDE is the implementation in superconducting hybrid structures. In this case the SDE is achieved by means of the proximity effect. However, the optimal conditions for the SDE quality factor in hybrid devices remain unclear. In this study we consider the Superconductor/Ferromagnet/Topological insulator (S/F/TI) hybrid device and investigate the diode quality factor at different parameters of the hybrid structure. Consequently, we reveal important parameters that have crucial impact on the magnitude of the SDE quality factor., Comment: arXiv admin note: text overlap with arXiv:2302.06575

We study theoretically the shape of the current-phase relation in a Josephson junction comprising the Zeeman-split superconductors (ZSs) and a normal metal (N). We show that at low temperatures the Josephson current in the ZS/N/ZS junctions exhibits an additional reversal in direction at a certain phase difference $\varphi_c \in (0, \pi)$. Calculating the spectral Josephson current, the band-splitting due to the Zeeman interaction is shown to cause the level crossing in the spectra of the Andreev bound states and the sign reversal in the Josephson current. Additionally, we propose an alternative method to electrically control the critical phase difference $\varphi_c$ by tuning the Rashba spin-orbit coupling, eliminating the need for manipulating magnetizations., Comment: 8 pages, 10 figures

Currently, the superconducting diode effect (SDE) is actively discussed due to large application potential in superconducting electronics. In particular, the superconducting hybrid structures based on three-dimensional (3D) topological insulators are among the best candidates due to the strongest spin-orbit coupling (SOC). Most of the theoretical studies of the SDE focus either on full numerical calculation, which is often rather complicated or on the phenomenological approach. In the present paper we perform a comparison of the linearized and nonlinear microscopic approaches in the superconductor/ ferromagnet/ 3D topological insulator (S/F/TI) hybrid structure. Employing the quasiclassical Green's function formalism we solve the problem self-consistently. We show that the results obtained by the linearized approximation are not qualitatively different from the nonlinear solution. Main distinction in the results between the two methods is quantitative, i. e. they yield different supercurrent amplitudes. However, when calculating the so-called diode quality factor the quantitative difference is eliminated and both approaches can result in a good agreement.

We study the transport properties of a diffusive Josephson junction between two spin-split superconductors made of superconductor-ferromagnetic insulator bilayers (FIS) on top of a 3D topological insulator (TI). We derive the corresponding Usadel equation describing the quasiclassical Green's functions in these systems and first solve the equation analytically in the weak-proximity case. We demonstrate the appearance of an anomalous phase in the absence of an external magnetic field. We also explore non-reciprocal electronic transport. Specifically, we calculate the junction's diode efficiency $\eta$ by solving the Usadel equation. We obtain a sizable diode effect even at zero applied magnetic field. We discuss how the diode efficiency $\eta$ depends on the different parameters and find a non-monotonic behavior of $\eta$ with temperature., Comment: 9 pages, 6 figures

In this work, we study magnetization dynamics in superconductor-ferromagnet-superconductor thin-film structures. Results of the broad-band ferromagnetic resonance spectroscopy are reported for a large set of samples with varied thickness of both superconducting and ferromagnetic layers in a wide frequency, field, and temperature ranges. Experimentally the one-dimensional anisotropic action of superconducting torque on magnetization dynamics is established; its dependence on thickness of layers is revealed. It is demonstrated that experimental findings support the recently-proposed mechanism of the superconducting torque formation via the interplay between the superconducting kinetic inductance and magnetization precession at superconductor-ferromagnet interfaces., Comment: 7 pages, 3 figures, 50 references

The fragility of the chiral surface current of ($d_{zx}+id_{yz}$)-wave superconductor, a potential candidate for Sr$_2$RuO$_4$, against surface roughness is demonstrated utilizing the quasiclassical Eilenberger theory. Comparing the chiral surface currents of ($d_{zx}+id_{yz}$)-wave and ($p_{x}+ip_{y}$)-wave pairings, we conclude the chiral current for ($d_{zx}+id_{yz}$)-wave SC is much more fragile than that for the ($p_x+ip_y$)-wave one. The difference can be understood in terms of the orbital symmetry of the odd-frequency Cooper pairs arising at the surface. Our results show the ($d_{zx}+id_{yz}$)-wave scenario can explain the null spontaneous magnetization in Sr$_2$RuO$_4$ experiments., Comment: 6 pages, 5 figures

We theoretically investigate the effects of the weak magnetization on the local density of states of mesoscopic proximity structures, where two superconducting terminals are attached to a side surface of the diffusive ferromagnet wire with a phase difference. When there is no phase difference, the local density of states is significantly modified by the magnetization in both spin-singlet $s$-wave and spin-triplet $p$-wave cases. When the phase difference is $\pi$, the local density of stets is less modified by the magnetization compared with the in-phase case because of the destructive interference of Cooper pairs., Comment: 5 pages, 5 figures

Made of a thin non-superconducting metal (N) sandwiched by two superconductors (S), SNS Josephson junctions enable novel quantum functionalities by mixing up the intrinsic electronic properties of N with the superconducting correlations induced from S by proximity. Electronic properties of these devices are governed by Andreev quasiparticles [1] which are absent in conventional SIS junctions whose insulating barrier (I) between the two S electrodes owns no electronic states. Here we focus on the Josephson vortex (JV) motion inside Nb-Cu-Nb proximity junctions subject to electric currents and magnetic fields. The results of local (Magnetic Force Microscopy) and global (transport) experiments provided simultaneously are compared with our numerical model, revealing the existence of several distinct dynamic regimes of the JV motion. One of them, identified as a fast hysteretic entry/escape below the critical value of Josephson current, is analyzed and suggested for low-dissipative logic and memory elements., Comment: 11 pages, 3 figures, 1 table, 43 references

It is well-known that the ground state of homogeneous superconducting systems with spin-orbit coupling (SOC) in the presence of the Zeeman field is the so-called helical state, which is characterized by the phase modulation of the order parameter, but zero supercurrent density. In this work we investigate the realization of the helical state in a hybrid system with spatially separated superconductivity and exchange field by considering S/F bilayer on top of a 3D topological insulator. This system is characterized by strong spin-momentum locking and, consequently, provides the most favorable conditions for the helical state generation. The analysis is based on the microscopic theory in terms of the quasiclassical Green's functions. We demonstrate that in the bilayer the helical state survives if the exchange field has non-zero component perpendicular to the S/F interface even in spite of the fact that the superconducting order parameter and the exchange field are spatially separated. At the same time, in this spatially inhomogeneous situation the helical state is accompanied by the spontaneous currents distributed over the bilayer in such a way as to have zero average. Further, we show that this hybrid helical state gives rise to nonreciprocity in the system. We demonstrate the realization of the superconducting diode effect and show that the degree of nonreciprocity is very large in the considered system due to the strongest possible value of the spin-momentum locking.

The tangential YORP effect is a radiation pressure torque produced by asymmetric thermal emission by structures on the asteroid surface. As such structures, previous works considered boulders of different shapes lying on the surface of the asteroid. We study the tangential YORP produced by the rough interface of the asteroid's regolith. We create an approximate analytic theory of heat conduction on a slightly non-flat sinusoidal surface. We analyze the published data on the small-scale shape of the asteroid (162173) Ryugu and estimate its tangential YORP due to the surface roughness. We derive an analytic formula that expresses the TYORP of a sinusoidal surface in terms of its geometric and thermal properties. TYORP is maximal at the thermal parameter of the order of unity and for the shape irregularities of the order of the thermal wavelength. Application of this equation to Ryugu predicts TYORP, which is 5-70 times greater than its normal YORP effect. The contribution of the small-scale regolith roughness to the YORP effect of the asteroid can be comparable to the normal YORP and the tangential YORP produced by boulders. The same theory can describe roughness on the asteroid boulders, thus adding a new term to the previously considered TYORP created by boulders., Comment: Accepted to Astronomy and Astrophysics

We derive a boundary condition for the Nambu Keldysh Green's function in diffusive normal metal / unconventional superconductor junctions applicable for mixed parity pairing. Applying this theory to a 1d model of $s+p$-wave superconductor, we calculate LDOS in DN and charge conductance of DN / $s+p$-wave superconductor junctions. When the $s$-wave component of the pair potential is dominant, LDOS has a gap like structure at zero energy and the dominant pairing in DN is even-frequency spin-singlet $s$-wave. On the other hand, when the $p$-wave component is dominant, the resulting LDOS has a zero energy peak and the dominant pairing in DN is odd-frequency spin-triplet $s$-wave. We show the robustness of the quantization of the conductance when the magnitude of $p$-wave component of the pair potential is larger than that of $s$-wave one. These results show the robustness of the anomalous proximity effect specific to spin-triplet superconductor junctions., Comment: 47 pages, 9 figures

An asteroid pair can be described as two asteroids with highly similar heliocentric orbits that are genetically related but not gravitationally bound. They can be produced by asteroid collisions or rotational fission. Although over 200 asteroid pairs are known, many more are remaining to be identified, especially among the newly discovered asteroids. The purpose of our work is to find new asteroid pairs in the inner part of the main belt with a new pipeline for asteroid pair search, as well as to validate the pipeline on a sample of known asteroid pairs. Initially, we select pair candidates in the five-dimensional space of osculating orbital elements. Then the candidates are confirmed using numerical modeling with the backtrack integration of their orbits including the perturbations from the largest main-belt asteroids, as well as the influence of the non-gravitational Yarkovsky effect. We performed a survey of the inner part of the main belt and found 10 new probable asteroid pairs. Their estimated formation ages lie between 30 and 400 kyr. In addition, our pipeline was tested on a sample of 17 known pairs, and our age estimates agreed with the ones indicated in literature in most of the cases., Comment: Accepted to A&A. 10 pages, 3 figures, 3 tables

In this work, we briefly overview various options for Josephson junctions which should be scalable down to nanometer range for utilization in nanoscale digital superconducting technology. Such junctions should possess high values of critical current, $I_c$, and normal state resistance, $R_n$. Another requirement is the high reproducibility of the junction parameters across a wafer in a fabrication process. We argue that Superconductor - Normal metal - Superconductor (SN-N-NS) Josephson junction of "variable thickness bridge" geometry is a promising choice to meet these requirements. Theoretical analysis of SN-N-NS junction is performed in the case where the distance between the S-electrodes is comparable to the coherence length of the N-material. The restriction on the junction geometrical parameters providing the existence of superconductivity in the S-electrodes is derived for the current flowing through the junction of an order of $I_c$. The junction heating, as well as available mechanisms for the heat removal, is analyzed. The obtained results show that an SN-N-NS junction with a high (sub-millivolt) value of $I_cR_n$ product can be fabricated from a broadly utilized combination of materials like Nb/Cu using well-established technological processes. The junction area can be scaled down to that of semiconductor transistors fabricated in the frame of a 40-nm process.

In this work, the ultra-strong photon-to-magnon coupling is demonstrated for on-chip multilayered superconductor/ferromagnet/insulator hybrid thin film structures reaching the coupling strength above 6 GHz, the coupling ratio about 0.6, the single-spin coupling strength about 350 Hz, and cooperativity about 10^4. High characteristics of coupling are achieved owing to a radical suppression of the photon phase velocity in electromagnetic resonator. With achieved coupling the spectrum reveals inapplicability of the Dicke model, and evidences contribution of the diamagnetic A^2 interaction term in the Hamiltonian of the system, which satisfies the Thomas-Reiche-Kuhn sum rule. The contribution of the A^2 term denotes validity of the Hopfield quantum model and manifests observation of a different hybrid polariton quasi-particle, namely, the plasmon-magnon polariton., Comment: 6 pages, 2 figures, 43 references

The Yarkovsky--O'Keefe--Radzievskii--Paddack (YORP) effect governs the spin evolution of small asteroids. The axial component of YORP, which alters the rotation rate of the asteroid, is mostly independent of its thermal inertia, while the obliquity component is very sensitive to the thermal model of the asteroid. Here we develop a semi-analytic theory for the obliquity component of YORP. We integrate an approximate thermal model over the surface of an asteroid, and find an analytic expression for the obliquity component in terms of two YORP coefficients. This approach allows us to investigate the overall evolution of asteroid rotation state, and to generalize the results previously obtained in the case of zero thermal inertia. The proposed theory also explains how a non-zero obliquity component of YORP originates even for a symmetric asteroid due to its finite thermal inertia. In many cases, this causes equatorial planes of asteroids to align with their orbital planes. The studied non-trivial behavior of YORP as a function of thermal model allows for a new kind of rotational equilibria, which can have important evolutionary consequences for asteroids., Comment: Accepted to AJ

We study Superconductor/Ferromagnet/Superconductor junctions with CuNi, PtNi, or Ni interlayers. Remarkably, we observe that supercurrents through Ni can be significantly larger than through diluted alloys. The phenomenon is attributed to the dirtiness of disordered alloys leading to a short coherence length despite a small exchange energy. To the contrary, pure Ni is clean resulting in a coherence length as long as in a normal metal. Analysis of temperature dependencies of critical currents reveals a crossover from short (dirty) to long (clean) range proximity effects in Pt1-xNix with increasing Ni concentration. Our results point out that structural properties of a ferromagnet play a crucial role for the proximity effect and indicate that conventional strong-but-clean ferromagnets can be advantageously used in superconducting spintronic devices., Comment: 14 pages, 8 figures

Less than one percent of the discovered small solar system objects have highly inclined orbits ($i>60^{\circ}$), and revolve around the Sun on near-polar or retrograde orbits. The origin and evolutionary history of these objects are not yet clear. In this work we study the surface properties and orbital dynamics of selected high-inclination objects. BVRI photometric observations were performed in 2019-2020 using the 2.0m telescope at the Terskol Observatory and the 2.6m telescope at the Crimean Astrophysical Observatory. Additionally, we searched for high-inclination objects in the Sloan Digital Sky Survey and Pan-STARRS. The dynamics of the selected objects was studied using numerical simulations. We obtained new photometric observations of six high-inclination objects. All of the objects have similar $B-V$, $V-R$, $R-I$ colours, which are close to those of moderately red TNOs and grey Centaurs. The photometric data that were extracted from the all-sky surveys also correspond to moderately red surfaces of high-inclination objects. No signs of ultra-red material on the surface of high-inclination asteroids were found, which supports the results of previous works. The comet C/2018 DO4 (Lemmon) revealed some complex morphology with structures that could be associated with particles that were ejected from the cometary nucleus. For objects 2013 LU28, 2015 KZ120, and 2020 EP we estimated future and past lifetimes on their orbits. It appears that the orbits of considered objects are strongly chaotic, and with the available accuracy of the orbital elements no reliable predictions can be made about their distant past or future. The lifetimes of high-inclination objects turned out to be highly non-sensitive to the precision of the orbital elements, and to the Yarkovsky orbital drift.

In the following paper we investigate the critical temperature $T_c$ behavior in the two-dimensional S/TI (S denotes superconductor and TI - topological insulator) junction with a proximity induced in-plane helical magnetization in the TI surface. The calculations of $T_c$ are performed using the general self-consistent approach based on the Usadel equations in Matsubara Green's functions technique. We show that the presence of the helical magnetization leads to the nonmonotonic behavior of the critical temperature as a function of the topological insulator layer thickness., Comment: submitted to Physical Review B

Magnetic flux quantization in superconductors allows the implementation of fast and energy-efficient digital superconducting circuits. However, the information representation in magnetic flux severely limits their functional density presenting a long-standing problem. Here we introduce a concept of superconducting digital circuits that do not utilize magnetic flux and have no inductors. We argue that neither the use of geometrical nor kinetic inductance is promising for the deep scaling of superconducting circuits. The key idea of our approach is the utilization of bistable Josephson junctions allowing the representation of information in their Josephson energy. Since the proposed circuits are composed of Josephson junctions only, they can be called all-Josephson junction (all-JJ) circuits. We present a methodology for the design of the circuits consisting of conventional and bistable junctions. We analyze the principles of the circuit functioning, ranging from simple logic cells and ending with an 8-bit parallel adder. The utilization of bistable junctions in the all-JJ circuits is promising in the aspects of simplification of schematics and the decrease of the JJ count leading to space-efficiency.

The critical step for future quantum industry demands realization of efficient information exchange between different-platform hybrid systems, including photonic and magnonic systems, that can harvest advantages of distinct platforms. The major restraining factor for the progress in certain hybrid systems is the fundamentally weak coupling parameter between the elemental particles. This restriction impedes the entire field of hybrid magnonics by making realization of scalable on-chip hybrid magnonic systems unattainable. In this work, we propose a general flexible approach for realization of on-chip hybrid magnonic systems with unprecedentedly strong coupling parameters. The approach is based on multilayered micro-structures containing superconducting, insulating and ferromagnetic layers with modified both photon phase velocities and magnon eigen-frequencies. Phenomenologically, the enhanced coupling strength is provided by the radically reduced photon mode volume. The microscopic mechanism of the phonon-to-magnon coupling in studied systems evidences formation of the long-range superconducting coherence via thick strong ferromagnetic layers. This coherence is manifested by coherent superconducting screening of microwave fields by the superconductor/ferromagnet/superconductor three-layers in presence of magnetization precession. This discovery offers new opportunities in microwave superconducting spintronics for quantum technologies., Comment: 17 pages, 3 figures, 1 table

Any population of asteroids, like asteroid families, will disperse in semi-major axis due to the Yarkovsky effect. The amount of drift is modulated by the asteroid spin state evolution which determines the balance between the diurnal and seasonal Yarkovsky force. The asteroid's spin state is, in turn, controlled in part by the YORP effect. The otherwise smooth evolution of an asteroid can be abruptly altered by collisions, which can cause impulsive changes in the spin state and can move the asteroid onto a different YORP track. In addition, collisions may also alter the YORP parameters by changing the superficial features and overall shape of the asteroid. Thus, the coupling between YORP and Yarkovsky is also strongly affected by the impact history of each body. To investigate this coupling we developed a statistical code modeling the time evolution of semi--major axis under YORP-Yarkovsky coupling. It includes the contributions of NYORP (normal YORP), TYORP (tangential YORP) and collisions whose effects are deterministically calculated and not added in a statistical way. We find that both collisions and TYORP increase the dispersion of a family in semi-major axis by making the spin axis evolution less smooth and regular. We show that the evolution of a family's structure with time is complex and collisions randomize the YORP evolution. In our test families we do not observe the formation of a 'YORP-eye' in the semi-major axis vs. diameter distribution, even after a long period of time. If present, the 'YORP-eye' might be a relic of an initial ejection velocity pattern of the collisional fragments.

We study the density of states (DOS) inside superconducting Josephson SIsFS junctions with complex interlayer consisting of a thin superconducting spacer 's' between insulator I and a ferromagnetic metal F. The consideration is focused on the local density of states in the vicinity of a tunnel barrier, and it permits to estimate the current-voltage characteristics in the resistive state of such junctions. We study the influence of the proximity effect and Zeeman splitting on the properties of the system, and we find significant sub-gap regions with non-vanishing DOS. We also find manifestations of the 0-$\pi$ transition in the behavior of DOS in a thin s-layer. These properties lead to appearance of new characteristic features on I-V curves which provide additional information about electronic states inside the junction., Comment: 11 pages, 10 figures

In this work, magnetization dynamics is studied in superconductor/ferromagnet/superconductor three-layered films in a wide frequency, field, and temperature ranges using the broad-band ferromagnetic resonance measurement technique. It is shown that in presence of both superconducting layers and of superconducting proximity at both superconductor/ferromagnet interfaces a massive shift of the ferromagnetic resonance to higher frequencies emerges. The phenomenon is robust and essentially long-range: it has been observed for a set of samples with the thickness of ferromagnetic layer in the range from tens up to hundreds of nanometers. The resonance frequency shift is characterized by proximity-induced magnetic anisotropies: by the positive in-plane uniaxial anisotropy and by the drop of magnetization. The shift and the corresponding uniaxial anisotropy grow with the thickness of the ferromagnetic layer. For instance, the anisotropy reaches 0.27~T in experiment for a sample with 350~nm thick ferromagnetic layer, and about 0.4~T in predictions, which makes it a ferromagnetic film structure with the highest anisotropy and the highest natural resonance frequency ever reported. Various scenarios for the superconductivity-induced magnetic anisotropy are discussed. As a result, the origin of the phenomenon remains unclear. Application of the proximity-induced anisotropies in superconducting magnonics is proposed as a way for manipulations with a spin-wave spectrum., Comment: 10 pages, 6 figures

We study theoretically the Josephson effect between two time-reversal two-band superconductors, where we assume the equal-time spin-singlet $s$-wave pair potential in each conduction band. %as well as the band asymmetry and the band hybridization in the normal state. The superconducting phase at the first band $\varphi_1$ and that at the second band $\varphi_2$ characterize a two-band superconducting state. We consider a Josephson junction where an insulating barrier separates two such two-band superconductors. By applying the tunnel Hamiltonian description, the Josephson current is calculated in terms of the anomalous Green's function on either side of the junction. We find that the Josephson current consists of three components which depend on three types of phase differences across the junction: the phase difference at the first band $\delta\varphi_1$, the phase difference at the second band $\delta\varphi_2$, and the difference at the center-of-mass phase $\delta(\varphi_1+\varphi_2)/2$. A Cooper pairs generated by the band hybridization carries the last current component. In some cases, the current-phase relationship deviates from the sinusoidal function as a result of time-reversal symmetry breaking down., Comment: 6 page, 2 figures

We have investigated the critical temperature behavior in periodic superconductor/ ferromagnet (S/F) multilayers as a function of the ferromagnetic layer thickness $d_f$ and the interface transparency. The critical temperature $T_c(d_f)$ exhibits a damped oscillatory behavior in these systems due to an exchange field in the ferromagnetic material. In this work we have performed $T_c$ calculations using the self-consistent multimode approach, which is considered to be exact solving method. Using this approach we have derived the conditions of 0 or $\pi$ state realization in periodic S/F multilayers. Moreover, we have presented the comparison between the single-mode and multimode approaches and established the limits of applicability of the single-mode approximation, frequently used by experimentalists.

The article studies the elastic and locomotive properties of Miura-ori-type paper origami. The mechanics of a single paper crease is studied experimentally, and its non-elastic properties turn out to be crucial. The entire origami construction is then described as a collection of individual creases, its capability to launch small objects is evaluated, and the equation of motion is found. Thus, the height of the launched ball is studied theoretically and experimentally as a function of governing parameters., Comment: Accepted to the Emergent Scientist

We theoretically study the local density of states in superconducting proximity structure where two superconducting terminals are attached to a side surface of a normal-metal wire. Using the quasiclassical Green's function method, the energy spectrum is obtained for both of spin-singlet $s$-wave and spin-triplet $p$-wave junctions. In both of the cases, the decay length of the proximity effect at the zero temperature is limited by a depairing effect due to inelastic scatterings. In addition to the depairing effect, in $p$-wave junctions, the decay length depends sensitively on the transparency at the junction interfaces, which is a unique property to odd-parity superconductors where the anomalous proximity effect occurs., Comment: 11 pages, 9 figures

We observed the near-Earth asteroid (101955) Bennu from the ground in 1999 and 2005, and with the Hubble Space Telescope in 2012, to constrain its rotation rate. The data reveal an acceleration of $2.64 \pm 1.05 \times 10^{-6} \mathrm{deg\ day}^{-2}$, which could be due to a change in the moment of inertia of Bennu or to spin up from the YORP effect or other source of angular momentum. The best solution is within 1 sigma of the period determined by Nolan et al. (2013). The OSIRIS-REx mission will determine the rotation state independently in 2019. Those measurements should show whether the change in rotation rate is a steady increase (due, for example, to the YORP effect) or some other phenomenon. The precise shape and surface properties measured by the OSIRIS-REx science team will allow for a better understanding of variations in rotation rate of small asteroids.

In this work, magnetization dynamics is studied at low temperatures in a hybrid system that consists of thin epitaxial magnetic film coupled with superconducting planar microwave waveguide. The resonance spectrum was observed in a wide magnetic field range, including low fields below the saturation magnetization and both polarities. Analysis of the spectrum via a developed fitting routine allowed to derive all magnetic parameters of the film at cryogenic temperatures, to detect waveguide-induced uniaxial magnetic anisotropies of the first and the second order, and to uncover a minor misalignment of magnetic field. A substantial influence of the superconducting critical state on resonance spectrum is observed and discussed., Comment: 10 pages, 6 figures