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arXiv · 1405.6717

Mobile magnetic impurities in a Fermi superfluid: a route to designer molecules

Sarang Gopalakrishnan·Colin V. Parker·Eugene Demler
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Abstract

A magnetic impurity in a fermionic superfluid hosts bound quasiparticle states known as Yu-Shiba-Rusinov (YSR) states. We argue here that, if the impurity is mobile (i.e., has a finite mass), the impurity and its bound YSR quasiparticle move together as a midgap molecule, which has an unusual "Mexican-hat" dispersion that is tunable via the fermion density. We map out the impurity dispersion, which consists of an "atomic" branch (in which the impurity is dressed by quasiparticle pairs) and a "molecular" branch (in which the impurity binds a quasiparticle). We discuss the experimental realization and detection of midgap Shiba molecules, focusing on lithium-cesium mixtures, and comment on the prospects they offer for realizing exotic many-body states.

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Sarang Gopalakrishnan, Colin V. Parker, Eugene Demler. 2015-03-08. Mobile magnetic impurities in a Fermi superfluid: a route to designer molecules. https://doi.org/10.1103/physrevlett.114.045301

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