Tuning of the critical temperature of superconducting Nb thin films on helimagnetic MnSi substrate

Abstract Theoretical considerations suggest control over the critical temperature T C of a superconductor via the proximity effect with a magnetic system exhibiting a non-collinear spin structure. This proximity effect is proposed to be applied as superconducting spin valves consisting only of a single magnetic layer and a thin superconducting film promising more simple and compact devices. MnSi being an archetype of the B20 structure shows helimagnetic behavior below T N ≈ 29.5 K and B C1 ≈ 100 mT. We have prepared MnSi substrates with helimagnetic properties from tri-arc-Czochralski grown single crystals on which we deposited superconducting Nb thin films. Our investigations show a shift of T C in the Nb film upon reorientation of the spin helices in the substrate in qualitative agreement with the theoretical predictions.