Superconducting spintronics

Abstract

Traditional studies that combine spintronics and superconductivity have mainly focused on the injection of spin-polarized quasiparticles into superconducting materials. However, a complete synergy between superconducting and magnetic orders turns out to be possible through the creation of spin-triplet Cooper pairs, which are generated at carefully engineered superconductor interfaces with ferromagnetic materials. Currently, there is intense activity focused on identifying materials combinations that merge superconductivity and spintronics to enhance device functionality and performance. The results look promising: it has been shown, for example, that superconducting order can greatly enhance central effects in spintronics such as spin injection and magnetoresistance. Here, we review the experimental and theoretical advances in this field and provide an outlook for upcoming challenges in superconducting spintronics.At the interface between materials with radically different properties, new physical phenomena can emerge. A classical example of such an interface is that between a superconductor and a ferromagnet where the opposing electron orders destructively interfere; however, it turns out that under the right conditions at a superconductorferromagnet interface both superconductivity and spin-polarization can unite to create a new superconducting state that offers tantalizing possibilities for spin transport in which Joule heating and dissipation are minimized.Spintronics offers the potential for creating circuits in which logic operations controlled by spin currents can be performed faster and more energy efficient [1] than the charge-based equivalent in semiconductor transistor technologies. Spintronics is one of the most active areas of research and while it offers control of spin and charge at the nanometer scale, it has also found sensory applications in hard disk drive read heads via the giant magnetoresistance effect [2,3]. The idea of combining superconductivity with spintronics has historically focused on the net spin-polarization of quasiparticles in superconductors. It is interesting to note that the first spin transport experiments [4-6] involved ferromagnet-superconductor bilayers and predated non-superconducting spin transport experiments [8]. As will be discussed in this review, it is possible to create pseudo-chargeless spin-1/2 excitations in superconductors [7] which have extremely long spin lifetimes.Recently, a more complete synergy between superconductivity and spintronics has been made possible through the discovery of spin-triplet Cooper pairs at superconductor-ferromagnet interfaces. Non-superconducting spin currents are generated by passing charge currents through ferromagnetic materials. As will be explained in this review, spin currents can also be generated by passing supercurrents through ferromagnetic materials. Charge flow within superconductors is carried by Cooper pairs which consist of interacting pairs of electrons [9]. The idea of combining superconducting and magnetic order wa...

Isolation of proximity-induced triplet pairing channel in a superconductor/ferromagnet spin valve

“…Spin valves have good prospects for use as passive elements of superconducting spintronic devices and should operate with a change of the direction of a weak external magnetic field. The manifestation of this effect in S/F systems with a good contact between the metallic ferromagnetic and superconducting layers prepared from ordinary metals and conventional ferromagnets was confirmed in a large number of experimental studies (see, for example, recent reviews [2][3][4] and references therein). Recent theoretical studies (see, for example,reviews [2][3][4][5][6][7][8]) have predicted the generation of a long-range triplet component of a superconducting condensate in S/F-structures.…”

“…The manifestation of this effect in S/F systems with a good contact between the metallic ferromagnetic and superconducting layers prepared from ordinary metals and conventional ferromagnets was confirmed in a large number of experimental studies (see, for example, recent reviews [2][3][4] and references therein). Recent theoretical studies (see, for example,reviews [2][3][4][5][6][7][8]) have predicted the generation of a long-range triplet component of a superconducting condensate in S/F-structures. As follows from the theory proposed by Fominov et al [9], the presence of a minimum of the superconducting transition temperature T c in e-mail: kamandi@mail.ru the vicinity of the orthogonal configuration of the magnetizations clearly indicates the generation of the longrange triplet component.…”

Probing the spiral magnetic phase in 6 nm textured erbium using polarised neutron reflectometry

“…For the emerging field of superconducting spintronics, Er is a strong candidate material to be the necessary source of inhomogeneous ferromagnetism [11,12]. In our previous work on 50 and 200 nm thick Er films, neutron diffraction was used to study magnetic Bragg peaks generated by the repeating magnetic structure.…”

User Software for Numerical Study of Josephson Junction with Magnetic Momenta

“…We show that our method can demonstrate a magnetization reversal effect [4]. This effect is very important for superconducting spintronics and could be useful in the frame of applications in the quantum computing field [1]. e-mail: atanasova@uni-plovdiv.bg…”

“…Josephson junctions in combination with magnetic moments occupy an important place in "hot" fields of science like spintronics, nanotechnology, superconductivity, condensed matter physics, low temperature physics [1]. They represent interest in a number of practical applications and are subjects in many research areas [2].…”