Magnetic pair breaking

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). 

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... 

A variety of other mechanisms, including hole localization, magnetic-pair breaking, or hybridization, have since been suggested (Guo and Temmerman 1990, Radousky 1992, Fehrenbacher and Rice 1993, Liechtenstein et al. 1995). 

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). 

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... 

There is a great deal of evidence that the cuprate-planes do not superconduct, not the least of which is that the cuprate-planes are sometimes adjacent to a magnetic (J O) pair-breaking rare-earth with L=0, such as Gd+3, which is unsplit by the crystal fields (because it has L=0). In such a case, as in the compound Gd2 Xe CuCk (which contains a CuC>2 plane, a Gd layer, an O2 layer, and a Gd layer) the Gd does break Cooper-like pairs and does destroy superconductivity in the adjacent layers (/Gd/O /Gd/). (An interstitial oxygen may also occupy a Gd layer.)... 

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