Pair-breaking

It is quite likely to find dense quark matter inside compact stars like neutron stars. However, when we study the quark matter in compact stars, we need to take into account not only the charge and color neutrality of compact stars and but also the mass of the strange quark, which is not negligible at the intermediate density. By the neutrality condition and the strange quark mass, the quarks with different quantum numbers in general have different chemical potentials and different Fermi momenta. When the difference in the chemical potential becomes too large the Cooper-pairs breaks or other exotic phases like kaon condensation or crystalline phase is more preferred to the BCS phase. 

The effect of thermal pion fluctuations on the specific heat and the neutrino emissivity of neutron stars was discussed in [27, 28] together with other in-medium effects, see also reviews [29, 30], Neutron pair breaking and formation (PBF) neutrino process on the neutral current was studied in [31, 32] for the hadron matter. Also ref. [32] added the proton PBF process in the hadron matter and correlation processes, and ref. [33] included quark PBF processes in quark matter. PBF processes were studied by two different methods with the help of Bogolubov transformation for the fermion wave function [31, 33] and within Schwinger-Kadanoff-Baym-Keldysh formalism for nonequilibrium normal and anomalous fermion Green functions [32, 28, 29],... 

An interesting theoretical prediction is that, similar as in the p-wave superconductors discussed in the next subsection, non-magnetic impurities in an antiferromagnetic superconductor cause pair breaking (Morozov 1980 Zwicknagl and Fulde 1981) whereas non-magnetic impurities in a non-magnetic superconductor are not expected to destroy superconductivity (Anderson 1959). 

Strong magnetic pair-breaking effects have been reported for (Y,/ )Pd2B2C. Also in these compounds the drop in Tc follows de Gennes scaling, with the exception of R — Ce, Eu and Yb (Ghosh et al. 2001). 

However, the influence of magnetic and nonmagnetic impurities appears to be opposite for the SC and SDW critical temperatures (Tconset and T rder, respectively). While influence of nonmagnetic impurities at depression of Tynsef jn thg system is only negligible but in the SDW system normal impurities (say, Zn) produce the pair-breaking effect (for electron-hole pairs), the effect well known in excitonic semimetals. Such behavior is in fact... 

Up to now,we always assumed a U coupled pair distribution to give a good description of both the proton 2p-2h excitation and of the neutron distribution over the valence model space.The quadrupole component of the proton-neutron force will induce 0+- 2+ pair breaking for both protons and neutrons which we call the core polarization effect.Thus,0 ground state and intruder wave functions... 

Similar effects have been obtained for the substitution of non-magnetic ions by magnetic ones. This concerns the strongly reduced Hc2 due to magnetic pair breaking (see, e.g., Takeya and El Massalami, 2004) and, additionally, the decreased positive curvature (Lan et al., 2000, 2001 Rathnayaka et al., 2003 see also... 

The investigation of pseudoquaternary compounds with two different rare earths on the R site in RNi2B2C revealed much insight into the pair-breaking... 

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