Distribution of pairing functions in superconducting spin valve SF1F2

The distribution of the spin-singlet component, the short-range spin-triplet component with zero projection, and the long-range spin-triplet component with projection ±1 of the superconducting pairing function has been obtained for different regimes of switching of a spin valve with a three-layer heterostructure (superconductor/ferromagnet/ferromagnet). The distribution of the components is discussed as the main reason for the behavior of the superconducting transition temperature as a function of the angle between the magnetic moments of the ferromagnetic layers in these regimes

Dependence of the Annual Asymmetry in NmF2 on Geomagnetic Latitude and Solar Activity

Abstract: The properties of the annual asymmetry in the electron density of the F2-layer maximum NmF2 at noon are analyzed based on the global empirical model of the F2-layer critical frequency median (SDMF2 model). As a characteristic of this asymmetry, we used the R index, i.e., the January/July ratio of the total (at a given and geomagnetically conjugate points) NmF2 density at noon averaged over all longitudes. It was found that the R index decreases with increasing solar activity at low geomagnetic latitudes (Φ < 31°–33°). At higher latitudes, the R index increases with an increase in solar activity. During low solar activity, the main R maximum is located at latitude Φ = 22°–24°. During high solar activity, this R maximum is located at Φ = 64°–66°. At latitude Φ = 22°–24° in the Northern and Southern hemispheres, the longitudinal average NmF2 density in January is higher than that in July for any level of solar activity. At Φ = 64°–66°, an increase in R with increasing solar activity is mainly caused by a January increase in NmF2 in the Northern Hemisphere. The global (average over all latitudes) R index increases with increasing solar activity. Additional analysis showed that the global R index decreases with increasing solar activity in the IRI model both with URSI option and, even more so, with CCIR option. This appears to be due to the limited amount of experimental data on the obtainment of the CCIR and URSI coefficients, especially over the oceans

Distribution of pairing functions in superconducting spin-valve switching modes

We investigated the critical temperature Tc of SF1F2 trilayers (S is a singlet superconductor, F1 and F2 are ferromagnetic metals), where the long-range triplet superconducting pairing is generated at canted magnetizations of the F layers. We examined the spin-singlet and spin-triplet pairing distributions and their amplitudes as a function of the layers thicknesses under different values of the angle a in the SF1F2 structure to clarify which one of the pairing distributions and how may affect the superconducting Tc

Proximity effects in superconducting triplet spin-valve F2/F1/S

We investigate the critical temperature Tc of F2/F1/S trilayers (Fi is a ferromagnetic metal and S is a singlet superconductor), where the long-range triplet superconducting component is generated at noncollinear magnetizations of the F layers. In this paper we demonstrate a possibility of the spin-valve effect mode selection (standard switching effect, the triplet spin-valve effect or reentrant Tc(α) dependence) by the variation of the F2/F1 interface transparency

Role of Interface Transparency and Exchange Field in the Superconducting Triplet Spin-Valve Effect

We study the superconducting transition temperature Tc of F2/F1/S trilayers (Fi is a metallic ferromagnet, S is a s-superconductor), where the long-range triplet superconducting component is generated at canted magnetizations of the F layers. In this paper we show that it is possible to realize different spin-valve effect modes - the standard switching effect, the triplet spin-valve effect, reentrant Tc(α) dependence or reentrant Tc(α) dependence with the inverse switching effect - by variation of the F2/F1 interface transparency or the exchange splitting energy. In addition, we show that positionof the Tc minimum can be changed by joint variation of the F2/F1 interface transparency and the layerthicknesses