Surprising lack of magnetism in the conductance channels of Pt atomic chains

Pt is known to show spontaneous formation of chains of metal atoms upon breaking a metallic contact. From model calculations these have been predicted to be spin polarized, which is reasonable in view of the Stoner enhanced susceptibility of bulk Pt and the increased density of states due to the reduced dimensionality. Here, we demonstrate that shot noise reveals information on the magnetic state of Pt atomic chains. Against all predictions, we find clear evidence for a non-magnetic ground state for the conductance channels of Pt atomic chains.