TY - JOUR
T1 - Temperature-composition phase diagrams for Ba 1-xSr xFe 2As 2 (0 ≤x≤ 1) and superconducting Ba 0.5Sr 0.5 (Fe 1-yCo y) 2As 2 (0 ≤y≤ 0.141)
AU - Mitchell, Jonathan E.
AU - Saparov, Bayrammurad
AU - Lin, Wenzhi
AU - Calder, Stuart
AU - Li, Qing
AU - Kalinin, Sergei V.
AU - Pan, Minghu
AU - Christianson, Andrew D.
AU - Sefat, Athena S.
PY - 2012/11/9
Y1 - 2012/11/9
N2 - Single crystals of mixed alkaline earth metal iron arsenide materials, Ba 1-xSr xFe 2As 2 with 0.185 ≤ x ≤ 0.762 and Ba 0.5Sr 0.5(Fe 1-yCo y) 2As 2 with 0.028 ≤ y ≤ 0.141, are synthesized via the self-flux method. Ba 1-xSr xFe 2As 2 display spin-density wave features (T N) at temperatures intermediate to the parent materials, x = 0 and 1, with T N(x) following an approximately linear trend. Cobalt doping of the 1:1 Ba:Sr mixture, Ba 0.5Sr 0.5(Fe 1-yCo y) 2As 2, results in a superconducting dome with maximum transition temperature of T C = 19 K at y = 0.092, close to the maximum transition temperatures observed in unmixed A(Fe 1-yCo y) 2As 2; however, an annealed crystal with y = 0.141 showed a T C increase from 11 to 16 K with a decrease in Sommerfeld coefficient γ from 2.58(2) to 0.63(2) mJ/(K2 mol atom). For the underdoped y = 0.053, neutron diffraction results give evidence that T N and structural transition (T O) are linked at 78 K, with anomalies observed in magnetization, resistivity, and heat capacity data, while a superconducting transition at T C 6 K is seen in resistivity and heat capacity data. Scanning tunneling microscopy measurements for y = 0.073 give Dynes broadening factor Γ = 1.15 and a superconducting gap Δ= 2.37 meV with evidence of surface inhomogeneity.
AB - Single crystals of mixed alkaline earth metal iron arsenide materials, Ba 1-xSr xFe 2As 2 with 0.185 ≤ x ≤ 0.762 and Ba 0.5Sr 0.5(Fe 1-yCo y) 2As 2 with 0.028 ≤ y ≤ 0.141, are synthesized via the self-flux method. Ba 1-xSr xFe 2As 2 display spin-density wave features (T N) at temperatures intermediate to the parent materials, x = 0 and 1, with T N(x) following an approximately linear trend. Cobalt doping of the 1:1 Ba:Sr mixture, Ba 0.5Sr 0.5(Fe 1-yCo y) 2As 2, results in a superconducting dome with maximum transition temperature of T C = 19 K at y = 0.092, close to the maximum transition temperatures observed in unmixed A(Fe 1-yCo y) 2As 2; however, an annealed crystal with y = 0.141 showed a T C increase from 11 to 16 K with a decrease in Sommerfeld coefficient γ from 2.58(2) to 0.63(2) mJ/(K2 mol atom). For the underdoped y = 0.053, neutron diffraction results give evidence that T N and structural transition (T O) are linked at 78 K, with anomalies observed in magnetization, resistivity, and heat capacity data, while a superconducting transition at T C 6 K is seen in resistivity and heat capacity data. Scanning tunneling microscopy measurements for y = 0.073 give Dynes broadening factor Γ = 1.15 and a superconducting gap Δ= 2.37 meV with evidence of surface inhomogeneity.
UR - http://www.scopus.com/inward/record.url?scp=84869118172&partnerID=8YFLogxK
U2 - 10.1103/PhysRevB.86.174511
DO - 10.1103/PhysRevB.86.174511
M3 - Article
AN - SCOPUS:84869118172
SN - 1098-0121
VL - 86
JO - Physical Review B - Condensed Matter and Materials Physics
JF - Physical Review B - Condensed Matter and Materials Physics
IS - 17
M1 - 174511
ER -