Positron annihilation study in SmFeAsO and SmFeAsO0.82F0.18

Hao, Y. P.; Chen, X. L.; Liu, R. H.; Kong, W.; Cheng, B.; Xu, H. X.; Chen, X. H.; Han, R. D.; Weng, H. M.; Du, H. J.; Ye, B. J.
February 2010
Applied Physics Letters;2/1/2010, Vol. 96 Issue 5, p052507
Academic Journal
SmFeAsO1-xFx polycrystalline samples were first studied by positron annihilation lifetime spectroscopy and Doppler-broadening spectroscopy, combined with the calculated results of positron lifetime. The experimental results agree well with the calculated positron bulk lifetime in SmFeAsO and SmFeAsF crystals. The temperature dependence of S-parameter shows a remarkable difference between the parent and superconductor. An abrupt jump of S-parameter is detected around 150 K in parent sample, however, two different slopes were shown below and above superconducting transition. The linearity S-T plot determines one-type of defects through the superconducting transition which must play an important role in superconductivity.


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