Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany.
Science. 2011 May 20;332(6032):940-4. doi: 10.1126/science.1202204.
Magnetic and superconducting interactions couple electrons together to form complex states of matter. We show that, at the atomic scale, both types of interactions can coexist and compete to influence the ground state of a localized magnetic moment. Local spectroscopy at 4.5 kelvin shows that the spin-1 system formed by manganese-phthalocyanine (MnPc) adsorbed on Pb(111) can lie in two different magnetic ground states. These are determined by the balance between Kondo screening and superconducting pair-breaking interactions. Both ground states alternate at nanometer length scales to form a Moiré-like superstructure. The quantum phase transition connecting the two (singlet and doublet) ground states is thus tuned by small changes in the molecule-lead interaction.
磁性和超导相互作用将电子耦合在一起，形成复杂的物质状态。我们表明，在原子尺度上，这两种相互作用可以共存并竞争，以影响局域磁矩的基态。在 4.5 开尔文下的局域光谱表明，吸附在 Pb(111)上的锰酞菁（MnPc）形成的自旋为 1 的系统可以处于两种不同的磁基态。这取决于康登屏蔽和超导对破坏相互作用之间的平衡。这两种基态在纳米尺度上交替，形成类似莫尔超结构。连接这两个（单态和双态）基态的量子相变可以通过分子与引线相互作用的微小变化来调节。
