Место издания:Bogoliubov Laboratory of Theoretical Physics, Dubna
Первая страница:39
Аннотация:Superconducting electronics is widely used in many areas, from the implementation of quantumcomputers, to the creation of terahertz detectors. Further miniaturization of the elementbase of superconducting logic is faced with the need to take into account the featuresof the electronic team in hybrid structures. Thus, the spin-orbit interaction that occurs inheavy metals or in 2D structures can significantly affect the dynamics of superconductingdevices. And ferromagnetic systems with non-collinear magnetization have prospects forthe implementation of memory elements. In this work, we studied the S-N(SO)-F structure,which is a series-connected S-superconductor, a thin film of N-normal metal with spin-orbit(CO) interaction, and an F-ferromagnet with an arbitrary direction of magnetization. Toanalyze the system, the Usadel equations were used, on the basis of which the numericalcalculation tools were used to find the value of the order parameter at the free boundary ofthe S-layer. The study analyzed the dynamics of Green’s functions: the S-layer pumps a ferromagnetwith singlet superconductivity; in the F layer, Cooper singlet pairs are depairedinto triplet pairs under the influence of the exchange energy h; further, penetrating into theN-layer, the triplet functions mix with each other and begin to decay, which leads to an increasein the singlet function and, ultimately, an increase in the order parameter. Thus, COinteraction can prevent the destruction of superconductivity by a ferromagnet. Moreover,the maximum effect is achieved at those magnetization rotation angles co-directional withthe direction of the spin-orbit interaction vector. By varying various parameters, such asthe lengths of the layers, the value of the exchange energy, and the temperature of the system,it was possible to detect a significant restoration of superconductivity upon a changein the orientation of the magnetization of a ferromagnet, which may be promising for theimplementation of a spin valve. Also in the work, a comparison was made with the implementationof a spin valve based on the S-F’-F system with two non-collinear ferromagnets.It was shown that such a system, upon magnetization reversal, can give a much greater effectof superconductivity recovery, but from a technical point of view, it is more complicatedto manufacture and control.