A new variant of the superconducting fulleride Rb3C60 is presented, with 3He atoms encapsulated in the C60 cages. The 3He nuclei act as sensitive NMR probes embedded in the material. The superconducting and normal states are characterised by 3He NMR. Evidence is found for co-existing vortex liquid and vortex solid phases below the superconducting transition temperature. A strong dependence of the spin-lattice relaxation time constant on spectral frequency is observed in the superconducting state, as revealed by two-dimensional NMR utilising an inverse Laplace transform. Surprisingly, this phenomenon persists, in attenuated form, at temperatures well above the superconducting transition.
@article{arxiv.2308.12812,
title = {Solid-state $^3\mathrm{He}$ NMR of the superconducting rubidium endofulleride $\mathrm{Rb_3(^3He@C_{60})}$},
author = {Murari Soundararajan and George R. Bacanu and Francesco Giustiniano and Mark C. Walkey and Gabriela Hoffman and Marina Carravetta and Martin R. Lees and Richard J. Whitby and Malcolm H. Levitt},
journal= {arXiv preprint arXiv:2308.12812},
year = {2023}
}