Quantum critical point in Ba(Fe<sub>1-x</sub>Co<sub>x</sub>)<sub>2</sub>As<sub>2</sub> from London penetration depth measured by optical NV magnetometer

ORAL

Abstract

Lower critical field, Hc1, allows direct access to London penetration depth, λ, which provides an insight into the normal-state electronic properties inside the dome of superconductivity in temperature-doping phase diagram. Using recently developed minimally invasive optical NV-centers magnetometry and the revised demagnetization corrections, Hc1 was measured in single crystals of electron-doped Ba(Fe1-xCox)2As2 for several x- values. The measurements reveal a sharp peak in λ(x) near x=0.057, exactly the composition at which the long-range magnetic order becomes incommensurate. Together with previous observation of quantum critical point (QCP) under the dome of superconductivity in isovalent AsP122, our results provide strong evidence for a ubiquitous nature of QCP in iron pnictides at the disappearance of the long-range ordered magnetism at T=0.

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This work was supported by the US DOE, Office of Science, BES Materials Science and Engineering Division under contract # DE-AC02-07CH11358.

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Presenters

  • Kamal Joshi

    • Ames Laboratory and Iowa State University, Ames, IA, USA

Authors

  • Kamal Joshi

    • Ames Laboratory and Iowa State University, Ames, IA, USA

  • Naufer M Nusran

    • Ames Laboratory and Iowa State University, Ames, IA, USA

  • Kyuil Cho

    • Ames Laboratory US DOE, Ames, Iowa
    • Ames Laboratory
    • Ames Laboratory and Iowa state University, USA
    • Ames Laboratory and Iowa State University, Ames, IA, USA
    • Ames Laboratory and Department of Physics & Astronomy, Iowa State University, Ames, IA 50010, USA

  • Makariy Tanatar

    • Ames Laboratory
    • Ames Laboratory US DOE, Ames, Iowa
    • Ames Laboratory and Iowa State University, Ames, IA, USA
    • Ames Laboratory and Department of Physics & Astronomy, Iowa State University, Ames, IA 50010, USA

  • Sergey L. Bud'ko

    • Iowa State University
    • Ames Laboratory and Iowa State University, Ames, IA, USA
    • Department of Physics & Astronomy, Iowa State University
    • Department of Physics and Astronomy, Iowa State University
    • Department of physics and astronomy, Iowa State University/Ames Laboratory

  • Paul Canfield

    • Ames Laboratory and Dept. of Physics, Iowa State University
    • Ames Laboratory, U.S. DOE, Iowa State University, Ames, Iowa 50011, USA.
    • Ames Laboratory
    • Iowa State University
    • Department of Physics, Iowa State University, Ames Laboratory, Ames, Iowa 50011, USA
    • Ames Laboratory, Iowa State University
    • Ames Laboratory/Iowa State University
    • Iowa State University and Ames Laboratory
    • Ames Laboratory and Iowa State University, Ames, IA, USA
    • Ames Laboratory and Dept. of Phys. and Astro.,, Iowa State Univ.
    • Ames Laboratory and Department of Physics & Astronomy, Iowa State University, Ames, IA 50010, USA
    • Ames Lab & Dept of Physics and Astronomy, Iowa State University
    • Department of Physics & Astronomy, Iowa State University
    • Department of physics and astronomy, Iowa State University/Ames Laboratory
    • Physics, Iowa State University/Ames Laboratory
    • Ames Laboratory & Iowa State University
    • Physics, Iowa State University

  • Alex Levchenko

    • University of Wisconsin-Madison
    • University of Wisconsin, Madison, WI, USA

  • Ruslan Prozorov

    • Ames Laboratory US DOE, Ames, Iowa
    • Iowa State University
    • Ames Laboratory, Iowa State University
    • Ames Laboratory
    • Ames Laboratory and Iowa state University, USA
    • Ames Laboratory and Iowa State University, Ames, IA, USA
    • Ames Laboratory and Department of Physics & Astronomy, Iowa State University, Ames, IA 50010, USA