Abstract
In superconductors, a topological configuration of the superconducting order parameter called a superconducting vortex carries magnetization. Such a magnetic topological object behaves like a minute particle generating a magnetic flux. Since the flux is localized with a nanometer scale, the vortex provides a nano-scale probe for local magnetic fields. Here we show that information of magnetic stripes in insulators can be read out by using vortices in an adjacent superconductor film as a probe. The orientation and width of magnetic micro stripes are both transcribed into resistance change of the superconductor through the modulation of vortex mobility affected by local magnetization. By changing the direction of external magnetic fields, zero-field resistance changes continuously according to the stripe orientation, and its modulation magnitude reaches up to 100%. The width of the stripes can also be estimated from the oscillatory magnetoresistance. Our results demonstrate a new possibility for non-volatile analog memory devices based on topological objects.
Highlights
In superconductors, a topological configuration of the superconducting order parameter called a superconducting vortex carries magnetization
The result shows that an external magnetic field can control the orientation of magnetic stripes
It is notable that the resistance ratio ρα(H = 0)/ρα=90°(H = 0) changes from 50% to 100% upon changing α, which is much greater than the magnitude of the conventional anisotropic magnetoresistance (AMR) in magnets
Summary
A topological configuration of the superconducting order parameter called a superconducting vortex carries magnetization. We show a mechanism for electric detection of magnetic-stripe information by using topological objects, superconducting vortices in superconductor/ferrimagnetic-insulator bilayers. Laboratory of Materials Modification by Laser, Ion, and Electron Beams (Ministry of Education), School of Materials electric detection of the internal magnetic structure in the magnet is possible by measuring resistance caused by vortex motion[9] in the superconductor film; by applying a bias current to the superconducting layer, the current induces vortex motion along the direction perpendicular to the current, generating voltage parallel to the current via the vortex-Josephson effect, and finite resistance is produced: the vortex flow resistance[9]. By using the anisotropic transport of vortices, information of magnetic stripes can be detected, as demonstrated below
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