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

Antiferromagnetic fluctuations in a quasi-two-dimensional organic superconductor detected by Raman spectroscopy

Natalia Drichko, Rudi Hackl, and John A. Schlueter
Phys. Rev. B 92, 161112(R) – Published 15 October 2015
PDFHTMLExport Citation
Abstract
Authors
Article Text
  • ACKNOWLEDGMENTS
    • Supplemental Material
    References

    Abstract

    Using Raman scattering, the quasi-two-dimensional organic superconductor κ−(BEDT−TTF)2Cu[N(CN)2]Br (Tc=11.8 K) and the related antiferromagnet κ−(BEDT−TTF)2Cu[N(CN)2]Cl are studied. Raman scattering provides unique spectroscopic information about magnetic degrees of freedom that has been otherwise unavailable on such organic conductors. Below T=200 K a broad band at about 500 cm−1 develops in both compounds. We identify this band with two-magnon excitation. The position and the temperature dependence of the spectral weight are similar in the antiferromagnet and in the metallic Fermi liquid. We conclude that antiferromagnetic correlations are similarly present in the magnetic insulator and the Fermi-liquid state of the superconductor.

    • Figure
    • Figure
    • Figure
    • Figure
    • Received 21 July 2015
    • Revised 1 October 2015

    DOI:https://doi.org/10.1103/PhysRevB.92.161112

    ©2015 American Physical Society

    Authors & Affiliations

    Natalia Drichko1,*, Rudi Hackl2, and John A. Schlueter3

    • 1Department of Physics and Astronomy, Johns Hopkins University, Baltimore Maryland 21218, USA
    • 2Walther Meissner Institut, Bayerische Akademie der Wissenschaften, 85748 Garching, Germany
    • 3Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA and National Science Foundation (NSF), Arlington, Virginia 22230, USA

    • *Corresponding author: drichko@jhu.edu

    Article Text (Subscription Required)

    Click to Expand

    Supplemental Material (Subscription Required)

    Click to Expand

    References (Subscription Required)

    Click to Expand
    Issue

    Vol. 92, Iss. 16 — 15 October 2015

    Reuse & Permissions
    Access Options
    CHORUS

    Article Available via CHORUS

    Download Accepted Manuscript
    Author publication services for translation and copyediting assistance advertisement

    Authorization Required

    Log In
    Other Options
    ×

    Images

    • Figure 1
      Figure 1

      (a) Schematic phase diagram for BEDT-TTF-based materials at half filling. The studied compounds are indicated by a red and a blue vertical line. (b) Schematic structure of the κ-(BEDT-TTF)2Cu[N(CN)2]X (X=Cl, Br) layer. The (BEDT-TTF)2+1 dimers are encircled. The putative orientation of the spins is indicated in red. The magnetic unit cell is given in blue. Due to the orthorhombic structure of the crystallographic unit cell (black dashes), having dimensions a and c along the unit vectors â and ĉ, the magnetic unit cell is characterized by nearly equilateral triangles. The axes â′=1/2(â+ĉ) and ĉ′=1/2(ĉ−â) are considered approximately parallel (for theoretical purposes) to the axes of the magnetic unit cell. The hopping integral t (t′) and the exchange coupling J (J′) are oriented along the full (dashed) blue line.

      Reuse & Permissions
    • Figure 2
      Figure 2

      Temperature dependence of Raman spectra of κ−(BEDT−TTF)2Cu[N(CN)2]Cl in b(ĉâ)b¯ polarization at temperatures between 15 and 200 K (solid lines). A dashed line shows a spectrum in b(ĉ′â′)b¯ polarization at 15 K. The inset shows a temperature dependence of the spectral weight of the two-magnon excitations, estimated by I(T)/I(15K).

      Reuse & Permissions
    • Figure 3
      Figure 3

      Temperature dependence of Raman spectra of κ−(BEDT−TTF)2Cu[N(CN)2]Br in b(ĉâ)b¯ polarization at temperatures between 15 and 213 K; spectra are shown with solid lines. A dashed line shows a spectrum in b(ĉ′â′)b¯ polarization at 15 K; note the absence of two-magnon maximum at 500 cm−1. The inset shows a temperature dependence of the spectral weight of the two-magnon excitations, estimated by I(T)/I(15K)

      Reuse & Permissions
    • Figure 4
      Figure 4

      Comparison of the 15 K Raman spectra of κ−(BEDT−TTF)2Cu[N(CN)2]Br (blue lines) and κ−(BEDT−TTF)2Cu[N(CN)2]Cl (red lines) at 200, 100, 55, and 15 K. The phonon lines are subtracted. The spectra show a comparison of the two-magnon features of the two materials.

      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
    ×