2004/04/29 by R. P. S. M. Lobo, Jiajing Tu, Lobo, R. P. S. M. +15
Physics and Astronomy · #Advanced Chemical Physics Studies #FOS: Physical sciences #Physics of Superconductivity and Magnetism #Superconductivity (cond-mat.supr-con) #Superconductivity in MgB2 and Alloys #cond-mat.supr-con
paper · pdf · doi:10.48550/arxiv.cond-mat/0404708
5 pages with 4 figures included
arxiv created 2004/04/29 · openalex publication_date 2004/04/29 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We studied the far-infrared reflectance of superconducting MgB2 in and out of equilibrium using pulsed synchrotron radiation. The equilibrium data can be described by a single energy gap at 2 Delta / hc = 43 cm-1. The fit improves slightly at lower frequencies when two gaps (at 30 cm-1 and 56 cm-1) are assumed to exist. The non equilibrium data is obtained when excess quasiparticles are generated in the MgB2 film by a laser pulse, decreasing the energy gap(s). The temperature dependence of the number of excess quasiparticles indicates that only a single gap near 30 cm-1 controls the non-equilibrium process. Fits to the photo-induced reflectance show the presence of the two gaps but weakening of an energy gap at 30 cm-1 only. Our data can be understood if one considers the picture where excited quasiparticles created by the laser impulse relax to the lowest gap band before recombining into Cooper pairs.