Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                

Absence of nematic order in the pressure-induced intermediate phase of the iron-based superconductor Ba0.85K0.15Fe2As2

Yan Zheng, Pok Man Tam, Jianqiang Hou, Anna E. Böhmer, Thomas Wolf, Christoph Meingast, and Rolf Lortz
Phys. Rev. B 93, 104516 – Published 14 March 2016
PDFHTMLExport Citation
Abstract
Authors
Article Text
  • INTRODUCTION
  • EXPERIMENTAL DETAILS
  • RESULTS
  • DISCUSSION
  • CONCLUDING REMARKS
  • ACKNOWLEDGMENTS
    • References

    Abstract

    The hole doped Fe-based superconductors Ba1−xAxFe2As2 (where A=Na or K) show a particularly rich phase diagram. It was observed that an intermediate reentrant tetragonal phase, in which the C4 fourfold rotational symmetry is restored, forms within the orthorhombic antiferromagnetically ordered stripe-type spin density wave state above the superconducting transition [S. Avci et al., Nat. Commun. 5, 3845 (2014); A. E. Böhmer et al., Nat. Commun. 6, 7911 (2015)]. A similar intermediate phase was reported to appear if pressure is applied to underdoped Ba1−xKxFe2As2 [E. Hassinger et al., Phys. Rev. B 86, 140502(R) (2012)]. Here we report data of the electric resistivity, Hall effect, specific heat, and the thermoelectric Nernst and Seebeck coefficients measured on a Ba0.85K0.15Fe2As2 single crystal under pressure up to 5.5 GPa. The data reveal a coexistence of the intermediate phase with filamentary superconductivity. The Nernst coefficient shows a large signature of nematic order that coincides with the stripe-type spin density wave state up to optimal pressure. In the pressure-induced intermediate phase the nematic order is removed, thus confirming that its nature is a reentrant tetragonal phase.

    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    • Figure
    • Received 7 July 2015
    • Revised 17 February 2016

    DOI:https://doi.org/10.1103/PhysRevB.93.104516

    ©2016 American Physical Society

    Physics Subject Headings (PhySH)

    1. Research Areas
    Electrical conductivityNematic orderNernst effectPressure effectsSeebeck effectSpecific heat
    1. Physical Systems
    Pnictides
    Condensed Matter, Materials & Applied Physics

    Authors & Affiliations

    Yan Zheng1, Pok Man Tam1, Jianqiang Hou1, Anna E. Böhmer2,3, Thomas Wolf2, Christoph Meingast2, and Rolf Lortz1,*

    • 1Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
    • 2Institute for Solid State Physics, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe, Germany
    • 3Fakultät für Physik, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany

    • *Corresponding author: lortz@ust.hk

    Article Text (Subscription Required)

    Click to Expand

    References (Subscription Required)

    Click to Expand
    Issue

    Vol. 93, Iss. 10 — 1 March 2016

    Reuse & Permissions
    Access Options
    Author publication services for translation and copyediting assistance advertisement

    Authorization Required

    Log In
    Other Options
    ×

    Images

    • Figure 1
      Figure 1

      Experimental configuration in the gasket (gray ring on the edge of the picture) of the Bridgman cell on top of one anvil. (Left-hand photograph, right-hand sketch.) The dark rectangle on the right is the Ba0.85K0.15Fe2As2 single crystal, contacted by Au leads and two thermocouples (TC1 and TC2). The light gray stripe on the left is a foil of Pb in a four-probe resistance configuration that serves as a manometer.

      Reuse & Permissions
    • Figure 2
      Figure 2

      (a) Resistivity of Ba0.85K0.15Fe2As2 under various pressures up to 5.5 GPa. The inset shows details at the superconducting transition in the low-temperature regime. (b) Temperature derivative of the resistivity. The arrows mark the onset of nematic and stripe-type SDW order.

      Reuse & Permissions
    • Figure 3
      Figure 3

      Specific heat of Ba0.85K0.15Fe2As2 under pressures of 0.2, 2.3, and 3.0 GPa. The lower right-hand inset shows details at the superconducting transition temperature Tc. In the upper left-hand inset, an approximate phonon background has been subtracted. This clearly reveals the presence of a further anomaly at T1>Tc in the 2.3 and 3 GPa data.

      Reuse & Permissions
    • Figure 4
      Figure 4

      Temperature dependence of the Nernst coefficient ν=N/B in a field of 6 T applied perpendicular to the FeAs layers (black open dots), the zero-field thermopower (green squares, scaled for comparison), and the Sondheimer term Stanθ/B (red line) of Ba0.85K0.15Fe2As2 at pressures of (a) 2.3 GPa and (b) 3 GPa.

      Reuse & Permissions
    • Figure 5
      Figure 5

      Field dependence of the Hall coefficient at various temperatures at pressures of (a) 0.2 GPa and (b) 3 GPa.

      Reuse & Permissions
    • Figure 6
      Figure 6

      Phase diagram of Ba0.85K0.15Fe2As2 compiled from the resistivity, specific heat, and Nernst coefficient data (tet., tetragonal; orth., orthorhombic; SDW, stripe-type antiferromagnetic spin density wave state; SC, superconducting state). The stars are data taken from Ref. [22] for Ba0.84K0.16Fe2As2.

      Reuse & Permissions
    ×

    Sign up to receive regular email alerts from Physical Review B

    Log In

    Cancel
    ×

    Search

    Article Lookup

    Paste a citation or DOI
    Enter a citation
    ×