The magnetic susceptibility of YBa${}_2$Cu${}_3$O${}_{6+x}$ crystals: unusual Curie behavior and small contributions from charge density waves

Abstract

We report measurements of the magnetic susceptibility of twinned single crystals of YBa${}_2$Cu${}_3$O${}_{6+x}$ from just above their superconducting transition temperatures to 300 K with magnetic fields of up to 5 T applied parallel and perpendicular to the CuO${}_2$ planes at 7 values of $x$. Appropriate analysis allows the relatively small, but still important, Curie terms to be separated from other contributions to the susceptibility. Our data support a picture in which the Curie terms arise from oxygen disorder in the Cu-O chains. This agrees with published work on polycrystalline samples where the sample cooling rate was varied, but here we show that the Curie plots flatten out above 200 K. We identify small effects of charge density wave (CDW) instabilities in the temperature ($T$) derivative of the in-plane susceptibility $d{\chi }_{ab}(T)/dT$ and discuss their $x$-dependence. For $x=$0.67 we make a detailed comparison with published high energy X-ray diffraction data using a minimal model involving Fermi arcs, thereby obtaining values for the CDW energy gap and the Helmholtz free energy in a coherence volume. At 80 and 100 K the latter is comparable with, or smaller than $k_{B}T$ respectively, highlighting the probable importance of thermal fluctuations. We note that the effect of the Lorentz force on charge carriers in the Fermi arcs could provide a simple mechanism for enhancing the CDWs in high magnetic fields, as suggested by recent experiments.

11 pages, 10 Figures, accepted by Phys. Rev. B. References corrected

References in corpus (14)

• Direct observation of competition between superconductivity and charge density wave order in YBa2Cu3Oy
• Scanning tunneling spectroscopy of high-temperature superconductors
• Quantum oscillations and the Fermi surface in an underdoped high-Tc superconductor
• How Cooper pairs vanish approaching the Mott insulator in Bi2Sr2CaCu2O8+d
• Resonant X-ray Scattering Study of Charge Density Wave Correlations in YBa${}_2$Cu${}_3$O${}_{6+x}$
• Distinct Charge Orders in the Planes and Chains of Ortho-III-Ordered YBa${}_2$Cu${}_3$O${}_{6+\delta }$ Superconductors Identified by Resonant Elastic X-ray Scattering
• Quantum Oscillations in the Underdoped Cuprate YBa2Cu4O8
• Incipient charge order observed by NMR in the normal state of YBa2Cu3Oy
• Shubnikov-de Haas oscillations in YBa_2Cu_4O_8
• X-ray diffraction observation of charge density wave order at zero magnetic field in ortho-II YBa${}_2$Cu${}_3$O${}_{6.54}$
• Lifshitz critical point in the cuprate superconductor YBa2Cu3Oy from high-field Hall effect measurements
• Charge density wave fluctuations in La2-xSrxCuO4 and their competition with superconductivity
• Quasiparticle mass enhancement approaching optimal doping in a high-Tc superconductor
• Pseudogap, Superconducting Gap, and Fermi Arc in High-Tc Cuprates Revealed by Angle-Resolved Photoemission Spectroscopy

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