Double Stern-Gerlach experiments on Mn@Sn12 : Refocusing of a paramagnetic superatom

Abstract

We report magnetic double deflection experiments on cryogenically cooled $\mathrm{Mn}@{\mathrm{Sn}}_{12}$ clusters. Refocusing efficiencies of up to 90% are achieved by keeping the magnetic-flux density virtually constant between the two Stern-Gerlach magnets. The spin dynamics are probed by introducing magnetic-flux density variations along the molecular-beam path. We apply a microscopic model for the interpretation of our results taking the coupling of electronic spin and rotational degrees of freedom into account. The combination of our experimental and theoretical results reveals unexpected insights into the interplay between rotation and spin dynamics of small metal clusters depending on magnetic-field modulations.