Controlling supercurrents and their spatial distribution in ferromagnets

Abstract

Spin-triplet Cooper pairs induced in ferromagnets form the centrepiece of the emerging field of superconducting spintronics. Usually the focus is on the spin-polarization of the triplets, potentially enabling low-dissipation magnetization switching. However, the magnetic texture which provides the fundamental mechanism for generating triplets also permits control over the spatial distribution of supercurrent. Here we demonstrate the tailoring of distinct supercurrent pathways in the ferromagnetic barrier of a Josephson junction. We combine micromagnetic simulations with three-dimensional supercurrent calculations to design a disk-shaped structure with a ferromagnetic vortex which induces two transport channels across the junction. By using superconducting quantum interferometry, we show the existence of two channels. Moreover, we show how the supercurrent can be controlled by moving the vortex with a magnetic field. This approach paves the way for supercurrent paths to be dynamically reconfigured in order to switch between different functionalities in the same device.

Odd triplet superconductivity induced by a moving condensate

“…1(a), such pairs appear only upon applying the magnetic field B ⊥ h. Hence we claim to find the mechanism of the odd triplet superconductivity generated by the magnetic field. The formation of LRTs has important consequences in the transport properties [54][55][56][105][106][107] which can be directly measured using the electrical probes. Below we discuss two of them-the tunnel conductance and Josephson current.…”

Spin-valve Josephson junctions with perpendicular magnetic anisotropy for cryogenic memory

“…Examples include the tuning of the ground state phase difference across a junction from 0 to π by changing the thickness of the F layer [6][7][8][9] . The additional physics can also drive the generation of m s = ±1 spin-triplet pair correlations with spin projection along the magnetization axis of the F layer in the junction 10 , leading to pair propagation through the F layer over much longer distances than the singlet component [11][12][13][14][15][16][17] .…”

Planar Superconductor-Ferromagnet-Superconductor Josephson Junctions as Scanning-Probe Sensors

“…In recent years hybrid Superconductor-Ferromagnet (SF) devices are being actively studied. The competition between superconductivity and magnetism in SF heterostructures leads to new phenomena and functionality which is interesting for variety of novel electronic and spintronic components, [9] such as phase shifters [10][11][12][13], superconducting spin valves [14][15][16][17][18][19], memory cells [20][21][22][23].…”