Josephson current versus potential strength of the interface in ferromagnetic superconductors

Based on the scattering theory, we calculate the Josephson current in a junction between two ferromagnetic super-conductors as a function of the interface potential z. We consider the ferromagnetic superconductor （FS） in three different Cooper pairing states： spin singlet s-wave pairing （SWP） state, spin triplet opposite spin pairing （OSP） state, and spin triplet equal spin pairing （ESP） state. We find that the critical Josephson current as a function of z shows clear differences among the SWP, OSP, and ESP states. The obtained results can be used as a useful tool for determining the pair symmetry of the ferromagnetic superconductors.

Molecular stacking controlling coherent and incoherent singlet fission in polymorph rubrene single crystals Special Issue:Emerging Investigators

Singlet fission(SF)is an appealing process where one photoexcited singlet transforms to two triplets,which can overcome thermalization energy loss and improve solar cell efficiency.However,it remains unclear how intermolecular coupling,which is subject to molecular stacking,controls SF pathways and dynamics.Here,we prepared polymorph rubrene single crystals with different stacking geometries,including orthorhombic(Orth.),triclinic(Tri.),and monoclinic(Mono.)phases.By micro-area ultrafast spectroscopy,we find that Orth.and Tri.phases with closerπ-πstacking exhibit co-existing coherent and incoherent SF channels while loosely stacked Mono.phase shows only incoherent SF.Furthermore,incoherent SF is thermally activated in Orth.but barrierless in Mono.and Tri.phases.Quantum mechanical calculation reveals that different electronic coupling strength in different phases leads to different SF dynamics.This study demonstrates that molecular stacking governs SF dynamics through electronic coupling,providing guidance for designing efficient SF materials via crystal structural engineering.

Coexistence of isospin I=0 and I=1 pairings in asymmetric nuclear matter

The coexistence of neutron-neutron(n-n),proton-proton(p-p),and neutron-proton(n-p)pairings is investigated by adopting an effective density-dependent contact pairing potential.These three types of pairings can coexist only if the n-p pairing is stronger than the n-n and p-p pairings for the isospin asymmetric nuclear matter.In addition,the existence of n-n and p-p pairs might enhance n-p pairings in asymmetric nuclear matter when the n-p pairing strength is significantly stronger than the n-n and p-p ones.Conversely,the n-p pairing is reduced by the n-n and p-p pairs when the n-p pairing interaction approaches n-n and p-p pairings.