TY - JOUR
T1 - Anisotropy of the iron pnictide superconductor Ba(Fe1-xCo x)2As2 (x=0.074, Tc = 23 K)
AU - Tanatar, M. A.
AU - Ni, N.
AU - Martin, C.
AU - Gordon, R. T.
AU - Kim, H.
AU - Kogan, V. G.
AU - Samolyuk, G. D.
AU - Bud'ko, S. L.
AU - Canfield, P. C.
AU - Prozorov, R.
PY - 2009/3/3
Y1 - 2009/3/3
N2 - Anisotropies of electrical resistivity, upper critical field, London penetration depth, and critical currents have been measured in single crystals of the optimally doped iron pnictide superconductor Ba(Fe1-xCo x)2As2 (x=0.074 and Tc ∼ 23 K). The normal-state resistivity anisotropy was obtained by employing both the Montgomery technique and direct measurements on samples cut along principal crystallographic directions. The ratio γρ = ρc/ρa is about 4 ± 1 just above T c and becomes half of that at room temperature. The anisotropy of the upper critical field, γH = Hc2,ab/Hc2,c, as determined from specific-heat measurements close to Tc is in the range of 2.1-2.6, depending on the criterion used. A comparable low anisotropy of the London penetration depth, γλ = λc/λab, was recorded from tunnel diode resonator measurements and found to persist deep into the superconducting state. An anisotropy of comparable magnitude was also found in the critical currents, γj = jc,ab/jc,c, as determined from both direct transport measurements (∼1.5) and from the analysis of the magnetization data (∼3). Overall, our results show that iron pnictide superconductors manifest anisotropies consistent with essentially three-dimensional intermetallic compounds and bear little resemblance to cuprates.
AB - Anisotropies of electrical resistivity, upper critical field, London penetration depth, and critical currents have been measured in single crystals of the optimally doped iron pnictide superconductor Ba(Fe1-xCo x)2As2 (x=0.074 and Tc ∼ 23 K). The normal-state resistivity anisotropy was obtained by employing both the Montgomery technique and direct measurements on samples cut along principal crystallographic directions. The ratio γρ = ρc/ρa is about 4 ± 1 just above T c and becomes half of that at room temperature. The anisotropy of the upper critical field, γH = Hc2,ab/Hc2,c, as determined from specific-heat measurements close to Tc is in the range of 2.1-2.6, depending on the criterion used. A comparable low anisotropy of the London penetration depth, γλ = λc/λab, was recorded from tunnel diode resonator measurements and found to persist deep into the superconducting state. An anisotropy of comparable magnitude was also found in the critical currents, γj = jc,ab/jc,c, as determined from both direct transport measurements (∼1.5) and from the analysis of the magnetization data (∼3). Overall, our results show that iron pnictide superconductors manifest anisotropies consistent with essentially three-dimensional intermetallic compounds and bear little resemblance to cuprates.
UR - http://www.scopus.com/inward/record.url?scp=63149114745&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.79.094507
DO - 10.1103/PhysRevB.79.094507
M3 - Article
AN - SCOPUS:63149114745
SN - 1098-0121
VL - 79
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 9
M1 - 094507
ER -