Flux motion and isotropic effects in MgB2 near the critical temperature
Yükleniyor...
Dosyalar
Tarih
2012
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Springer
Erişim Hakkı
info:eu-repo/semantics/closedAccess
Özet
The anisotropic behaviour of polycrystalline MgB2 was studied in details by means of angle dependent magnetovoltage measurements (V-theta curves) at the temperatures near the critical temperature T-c, where theta is the angle between the external magnetic field H and the transport current I. The measurement of V-theta curves was carried out at fixed temperatures below T-c for different values of H and I in a range of theta = -20 degrees-200 degrees. Magnetovoltage measurements (V-H curves) were performed for perpendicular and parallel orientations of H with respect to I, i.e., the V-perpendicular to-H curves for (H) over right arrow perpendicular to(I) over right arrow and V-parallel to-H curves for (H) over right arrow parallel to(I) over right arrow. The analysis of V-theta curves does not give any agreement with V (theta) similar to sin(2) (theta) or any modified angular relationship, so that the measured dissipation is nearly independent of the angle between H and I. The isotropic effects observed in MgB2 were discussed in the frame of the continuum approximation, the discrete case and the flux line cutting associated with the double critical state model derived in the literature. Finally, it is concluded that structural disorder induced isotropic effects can explain the isotropic angular dissipation observed in V-theta, I-V and V-H curves.
Açıklama
Anahtar Kelimeler
MgB2
Kaynak
European Physical Journal B
WoS Q Değeri
Q3
Scopus Q Değeri
Cilt
85
Sayı
11
