The FFLO State in the Dimer Mott Organic Superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br

The superconducting phase diagram for a quasi-two-dimensional organic superconductor, κ-(BEDT-TTF)2Cu[N(CN)2]Br, was studied using pulsed magnetic field penetration depth measurements under rotating magnetic fields. At low temperatures, Hc2 was abruptly suppressed even by small tilts of the applied fields owing to the orbital pair-breaking effect. In magnetic fields parallel to the conducting plane, the temperature dependence of the upper critical field Hc2 exhibited an upturn and exceeded the Pauli limit field HP in the lower temperature region. Further analyses with the second derivative of the penetration depth showed an anomaly at 31–32 T, which roughly corresponded to HP. The origin of the anomaly should not be related to the orbital effect, but the paramagnetic effect, which is almost isotropic in organic salts, because it barely depends on the field angle. Based on these results, the observed anomaly is most likely due to the transition between the Bardeen-Cooper-Schrieffer (BCS) and the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states. Additionally, we discuss the phase diagram and physical parameters of the transition by comparing them with other FFLO candidates.

Design of Ultra Low Profile Inverted L Antenna Composed of CPW Printed on PET Sheet for IoT Application

The ultra low profile inverted L (ULPIL) antenna on a rectangular conducting plane is located above the lower conducting plane and numerically analyzed for the application of IoT. The coplanar waveguide (CPW) is inserted within the antenna element. The antenna element is printed on the polyethylene terephthalate (PET) sheet. The shift of the resonant frequency of this antenna is small due to the existence of lower conducting plane. The influence of the existence of the lower conducting plane can be neglected when the distance between the ULPIL antenna and the lower conducting plane is longer than 6 mm (0.049 wavelength). Therefore the ULPIL antenna may be promising for the IoT application.

Complementary spherical surface screens

Ideally conducting spherical screens (SS) are investigated in this work. Boundary conditions on the surface of the field inside the sphere and outside it give relations connecting the elements of the scattering matrix (SM) of SS. These relations make it possible to express 4 submatrices of the SS SM in terms of one submatrix. The problem of the relationship between the characteristics of additional SS is considered. This problem is an analogue of Babinet's problem on additional flat screens. Combining additional flat screens forms a perfectly conducting plane, and combining additional SS gives a perfectly conducting sphere. When establishing the relationship of the characteristics of additional SS, they are considered, on the one hand, as a system of two bodies. On the other hand, this system forms a perfectly conducting sphere, the SM of which is diagonal. Equating the SM of the system with the SM of an ideally conducting sphere gives the sought relationship between the SMs of additional SS. The results of numerical verification of the relationships for the SM of additional SS are presented. In numerical calculations, the dimensions of the SS SM, which are infinite in the general case, have to be limited, this leads to an error. It is shown that with an increase in the SM dimension, the error decreases, and the elements of the resulting matrix approach those of the SM of an ideally conducting sphere. This confirms the validity of the relations for the SM of additional SS. The interrelation of characteristics of additional SS obtained in this work is analogous to the Babinet principle for additional flat screens. We believe that it will turn out to be just as popular and useful in calculating spherical screens and antennas, as Babinet's principle for flat screens and flat antennas.

Scattering and diffraction of a uniform complex-source beam by a slit in a perfectly conducting plane screen

A new multipole solution in plane-polar coordinates for the scattering of an arbitrary TE- or TM-polarized incident field by an infinitely extended slit in a plane screen is derived. To this end a classical three-domain problem with a complete multipole expansion in each of the domains is formulated. The unknown multipole amplitudes are found from the continuity conditions of the tangential electric and magnetic field components. Finally an infinite system of linear equations is derived which can be approximated by a numerically tractable finite one leading to a solution with an arbitrary accuracy. The results are numerically successfully compared to those ones obtained by classically solving the strip problem using Mathieu functions and by a subsequent application of the rigorous form of the Babinet principle. Numerical results include the comparison of the scattered fields obtained for an incident uniform complex-source beam and for an incident plane wave.

Anisotropy of Lower Critical Field in Organic Layered Superconductor λ-(BETS)2GaCl4

The lower critical field of type-II organic layered superconductor l-(BETS)2GaCl4 has been estimated by magnetic measurements. The demagnetization factor of a needle-like sample shape has been taken into account for the measurements by applying the external field, parallel and perpendicular to the conducting plane. The lower critical field for the field parallel to the conducting plane is 5.5(2) G, in contrast with the previous studies. This allows us to discuss the anisotropy of lower critical field Hc1 in a quasi-two-dimensional organic layered superconductor l-(BETS)2GaCl4.

Lower Critical Field of Layered Organic Superconductor with Asymmetrical Donor κ-(MDT-TTF)2AuI2

We report magnetization measurement in the superconducting state of a type-II organic layered superconductor with asymmetrical donor k-(MDT-TTF)2AuI2. The demagnetization factor of a plate-like shape of the single crystal has been taken into account for the measurement by applying an external field perpendicular to the conducting plane. The superconducting transition temperature TC is determined to be 4.7 K through the detection of demagnetization signal. The lower critical field is 10.5±1.4 G. This result implies that the stable vortex state of k-(MDT-TTF)2AuI2 can be reached at the applied magnetic field above 105 Oe

Spurious radiation suppression in microstrip monopulse antenna

Purpose This paper aims to introduce a new novel microstrip monopulse comparator system to reduce the spurious radiation from the comparator and the feed network for achieving better radiation performance. Design/methodology/approach Two substrate layers have been used for the microstrip monopulse comparator system. The feed network and the comparator circuits are on the first substrate layer and the microstrip array antenna is on the second layer. The elements of the array antenna are novel square four-sided narrow rectangular slot antennas built on a conducting plane. A commercially available computational software, CST microwave studio, has been used for the analysis of the system. Findings Two substrate layers have been used for the microstrip monopulse comparator system. The feed network and the comparator circuits are on the first substrate layer and the microstrip array antenna is on the second layer. The elements of the array antenna are novel square four-sided narrow rectangular slot antennas built on a conducting plane. A commercially available computational software, CST microwave studio, has been used for the analysis of the system. Practical implications The system is proposed for tracking moving targets. Originality/value Novel slot radiators are introduced as radiating elements in this paper. The antenna arrangement shields the comparator and the feed network circuits, reducing the spurious radiation significantly.