Abstract
Quantum impurity models are prevalent throughout many body physics, providing some prime examples of strongly correlated systems. Aside from being of great interest in themselves they can provide deep insight into the effects of strong correlations in general. The classic example is the Kondo model wherein a magnetic impurity is screened at low energies by a non interacting metallic bath. Here we consider a magnetic impurity coupled to a quantum wire with pairing interaction which dynamically generates a mass gap. Using Bethe Ansatz we solve the system exactly finding that it exhibits both screened and unscreened phases for an antiferromagnetic impurity. We determine the ground state density of states and magnetization in both phases as well as the excitations. In contrast to the well studied case of magnetic impurities in superconductors we find that there are no intragap bound states in the spectrum. The phase transition is not associated to a level crossing but with quantum fluctuations.
Highlights
The basic quantum impurity model describes a single magnetic impurity coupled to a metallic electron bath
The physics of the Kondo effect underpins our understanding of many disparate systems ranging from quantum dots to heavy fermion materials [1,2] and provides a proving ground for many powerful many-body techniques [3,4,5,6,7]
A case of great interest is the interplay of the Kondo effect and superconductivity which has been intensely studied, both the impact of magnetic impurities on superconductivity [8,9,10,11] and more recently, the impact of superconductivity on the Kondo effect [12,13]
Summary
The basic quantum impurity model describes a single magnetic impurity coupled to a metallic electron bath. The attractive interactions among left and right moving electrons dynamically generate a superconducting mass gap , but as long-range order is not allowed in one dimension [14], the rigid phase correlations and the charge sector decouple from the gapped spin sector [15,16]. The phase transition occurs at the ratio of Kondo temperature to mass gap of TK / ≈ 0.32. This is reminiscent of a magnetic impurity in a three-dimensional superconductor [17,18,19,20,21,22,23]. In contrast, we find that there are no intragap bound states in the spectrum in either phase and so the phase transition is not due to a level crossing but to quantum fluctuations
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
