Pair density waves revealed by Andreev reflection spectra

The pair density wave (PDW) state is recently proposed to be present in high temperature superconductors.

Although there are several experimental evidences to support such a proposal, a direct

evidence that depends on the unique property of PDW state is still lacking. In this work we propose

to detect the PDW states by probing the Andreev reflection from the metal/insulator/PDW states

junction. The angular and energy dependence of the transport property of this heterostructure is

calculated by using the Blonder-Tinkham-Klapwijk formalism in lattice models. Nearly degenerate

ground states, from the renormalized mean-field theory of the t-t’-J models, such as the anti-phase

charge density wave and commensurate PDW with a node (nodal PDW), are studied. Unlike usual

BCS superconductors, reflected Andreev hole currents and normal quasi-particle currents can happen

together at several angles. These uniquely new features could be used to verify the existence of

the PDW in cuprates