Relaxation and pinning in spark-plasma sintered MgB2 superconductor

Milos Jirsa (1) , Michal Rameš (1) , Michael Rudolf Koblischka (2) , Anjela Koblischka-Veneva (2) , Kévin Berger (3) , Bruno Douine (3)

1 Institute of Physics ASCR
2 Institute of Experimental Physics
3 GREEN - Groupe de Recherche en Electrotechnique et Electronique de Nancy

The model of thermally activated relaxation developed and successfully tested on high-Tc superconductors [Phys. Rev. B 70 (2004) 0245251-9] was applied to magnetic data of a bulk spark-plasma sintered MgB2 sample to elucidate its magnetic relaxation behavior. MgB2 and the related borides form a superconductor class lying between classical and high-Tc superconductors. In accord with this classification, the relaxation phenomena were found to be about ten times weaker than in cuprates. Vortex pinning analyzed in terms of the field dependence of the pinning force density indicates a combined pinning by normal point-like defects and by grain surfaces. An additional mode of pinning at rather high magnetic fields (of still unknown origin) was observed.

Mots clés: Bulk MgB2 superconductor; magnetic properties; magnetic relaxation; critical currents; pinning force density

Domaines: Electromagnétisme; Supraconductivité [cond-mat.supr-con]; Energie électrique

Milos Jirsa, Michal Rameš, Michael Rudolf Koblischka, Anjela Koblischka-Veneva, Kévin Berger, et al.. Relaxation and pinning in spark-plasma sintered MgB2 superconductor. Superconductor Science and Technology, 2016, 29 (2), 025006, 8 p. ⟨10.1088/0953-2048/29/2/025006⟩. ⟨hal-01237167⟩