Abstract
Magnetoresistance is a multifaceted effect reflecting the diverse transport mechanisms exhibited by different kinds of plain materials and hybrid nanostructures; among other, giant, colossal, and extraordinary magnetoresistance versions exist, with the notation indicative of the intensity. Here we report on the superconducting magnetoresistance observed in ferromagnet/superconductor/ferromagnet trilayers, namely Co/Nb/Co trilayers, subjected to a parallel external magnetic field equal to the coercive field. By manipulating the transverse stray dipolar fields that originate from the out-of-plane magnetic domains of the outer layers that develop at coercivity, we can suppress the supercurrent of the interlayer. We experimentally demonstrate a scaling of the magnetoresistance magnitude that we reproduce with a closed-form phenomenological formula that incorporates relevant macroscopic parameters and microscopic length scales of the superconducting and ferromagnetic structural units. The generic approach introduced here can be used to design novel cryogenic devices that completely switch the supercurrent ‘on’ and ‘off’, thus exhibiting the ultimate magnetoresistance magnitude 100% on a regular basis.
Highlights
Interlayer[12,13,24]
The FM/SC/FM TLs should have a predictable behavior regarding the SMR magnitude to allow the design of cryogenic devices, with the possibility to be operated as ideal supercurrent switches, exhibiting a 100% SMR magnitude under the application of a relatively low parallel Hex
We experimentally demonstrate a scaling of the SMR magnitude that is modeled by a simple closed-form phenomenological formula that incorporates the relevant macroscopic parameters and microscopic length scales of the SC and FM structural units
Summary
Interlayer[12,13,24]. the SC interlayer experiences local magnetic fields that exceed either its lower-critical field (SMR relates to vortex-motion dissipation processes) or its upper-critical field (SMR relates to the charge-dependent orbital effect)[12,15]. We present experimental data and phenomenological modeling of the SMR effect that, in these TLs, is accompanied by an intense reentrance of the upper-critical field line, Hc2(T) close to the critical temperature[12,13,24]. SMR effect and reentrance of the upper-critical field line, Hc2(T). TCexp refers to the experimentally-recorded critical temperature, while TCext is estimated from the extrapolation of the high-field part of Hc2(T) to zero field. For the extrapolation we use the relation that holds in FM/SC/FM TLs subjected to a parallel magnetic field when the coherence length, ξ (T) gets on the order of the SC thickness, dSC25
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