Quantum critical point in Ba(Fe1-xCox)2As2 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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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