Magnetic Resonance of Superconducting Triplet Pairs – TRIPRES

Spin fluctuations are believed to play a crucial role in the pairing mechanisms of unconventional superconductors, and collective spin modes were central to the identification of the equal-spin pairing state of the superfluid 3He-A via nuclear magnetic resonance. Yet collective spin modes have never been observed in superconductors. Spin dynamics is difficult to investigate experimentally as the penetration of magnetic fields in bulk superconductors is inhomogeneous (Meissner effect). Using new (quasi-)2D materials, we propose to directly detect equal-spin triplet pairs (ESTP) with a novel magnetic resonance technique, complemented by transport measurements. We are motivated by preliminary evidence of a field-induced ESTP in bilayer NbSe2 tunnel spectra and anomalous Josephson phases in semiconducting devices, where proximity-induced triplet correlations are expected and can be gate-tunable. These experiments will be supported by microscopic and phenomenological theory.