Anisotropy of the upper critical field in a Co-doped BaFe2As2 single crystal

Journal Article · Thu Jan 01 04:00:00 EST 2009 · Journal of the Physical Society of Japan

DOI:https://doi.org/10.1143/JPSJ.78.084719· OSTI ID:964709

Kano, M. ^[1]; Kohama, Y. ^[2]; Graf, D. ^[1]; Balakirev, F F ^[2]; Sefat, A. S. ^[3]; McGuire, Michael A ^[4]; Sales, Brian C ^[4]; Mandrus, David ^[4]; Tozer, Stan ^[1]

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1. Florida State University
2. National High Magnetic Field Laboratory, Los Alamos National Lab, Los Alamos
3. Oak Ridge National Laboratory (ORNL)
4. ORNL

The temperature dependence of the upper critical magnetic field (H{sub c2}) in a BaFe{sub 1.84}Co{sub 0.16}As{sub 2} single crystal was determined via resistivity, for the inter-plane (H {perpendicular} ab) and in-plane (H {parallel} ab) directions in pulsed and static magnetic fields of up to 60 T. Suppressing superconductivity in a pulsed magnetic field at {sup 3}He temperatures permits us to construct an H{sub c2}-T phase diagram from quantitative H{sub c2}(0) values and determine its behavior in low temperatures. H{sub c2}(0) with H {parallel} ab [H{sub c2{parallel}} (0)] and H {perpendicular} ab [H{sub c2{perpendicular}} (0)] are -55 and -50 T respectively. These values are -1.2-1.4 times larger than the weak-coupling Pauli paramagnetic limit (H{sub p} = 1.84 T{sub c}), indicating that enhanced paramagnetic limiting is essential and this superconductor is unconventional. While H{sub c2} {parallel} ab is saturated at low temperature, H{sub c2} with H {perpendicular} ab (H{sub c2{perpendicular}}) exhibits almost linear temperature dependence towards T = 0 K which results in reduced anisotropy of H{sub c2} in low temperature. The anisotropy of H{sub c2} was -3.4 near T{sub c}, and decreases rapidly with lower temperatures reaching -1.1 at T=0.7 K.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 964709
• Journal Information: Journal of the Physical Society of Japan, Journal Name: Journal of the Physical Society of Japan Journal Issue: 8 Vol. 78; ISSN 0031-9015; ISSN JUPSAU
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANISOTROPY
ARSENIDES
BARIUM COMPOUNDS
COBALT
CRITICAL FIELD
DOPED MATERIALS
IRON ARSENIDES
MAGNETIC FIELDS
PHASE DIAGRAMS
SUPERCONDUCTIVITY
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE