TY - JOUR
T1 - Vortex phase diagram of Ba(Fe0.93Co0.07) 2As2 single crystals
AU - Prozorov, R.
AU - Ni, N.
AU - Tanatar, M. A.
AU - Kogan, V. G.
AU - Gordon, R. T.
AU - Martin, C.
AU - Blomberg, E. C.
AU - Prommapan, P.
AU - Yan, J. Q.
AU - Bud'ko, S. L.
AU - Canfield, P. C.
PY - 2008/12/1
Y1 - 2008/12/1
N2 - Irreversible magnetic properties of Ba(Fe0.93Co 0.07)2As2 single crystals were studied by using several techniques including transport, magnetization, and magneto-optics. The mixed-state response was found to be very similar to high-Tc cuprates, such as Y-Ba-Cu-O and Nd-Ce-Cu-O. In particular, we find a nonmonotonic "fishtail" shape of the magnetization loops M (T=const,H) and a corresponding feature in M (T,H=const) scans, as well as a very large magnetic relaxation rate. The supercurrent density, j, in the critical state was evaluated from magnetization and from direct transport measurements close to Tc. At 5 K we estimate a moderate j≈2.6±0.2×10 5 A/cm2. Analysis of the temperature and field dependencies of the magnetic relaxation is consistent with the collective pinning and creep (weak pinning and fast creep) model and suggests a crossover from the collective to the plastic creep regime in fields exceeding the field at which the fishtail magnetization is maximum. While the zero-field anisotropy of the magnetic properties in the superconducting state of Ba(Fe 0.93Co0.07)2As2 is small, the vortex behavior changes for different orientations of magnetic field with respect to the crystal axes, implying field-dependent anisotropy of pinning properties.
AB - Irreversible magnetic properties of Ba(Fe0.93Co 0.07)2As2 single crystals were studied by using several techniques including transport, magnetization, and magneto-optics. The mixed-state response was found to be very similar to high-Tc cuprates, such as Y-Ba-Cu-O and Nd-Ce-Cu-O. In particular, we find a nonmonotonic "fishtail" shape of the magnetization loops M (T=const,H) and a corresponding feature in M (T,H=const) scans, as well as a very large magnetic relaxation rate. The supercurrent density, j, in the critical state was evaluated from magnetization and from direct transport measurements close to Tc. At 5 K we estimate a moderate j≈2.6±0.2×10 5 A/cm2. Analysis of the temperature and field dependencies of the magnetic relaxation is consistent with the collective pinning and creep (weak pinning and fast creep) model and suggests a crossover from the collective to the plastic creep regime in fields exceeding the field at which the fishtail magnetization is maximum. While the zero-field anisotropy of the magnetic properties in the superconducting state of Ba(Fe 0.93Co0.07)2As2 is small, the vortex behavior changes for different orientations of magnetic field with respect to the crystal axes, implying field-dependent anisotropy of pinning properties.
UR - https://www.scopus.com/pages/publications/57749105292
U2 - 10.1103/PhysRevB.78.224506
DO - 10.1103/PhysRevB.78.224506
M3 - Article
AN - SCOPUS:57749105292
SN - 1098-0121
VL - 78
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 22
M1 - 224506
ER -