Nearly Free Electrons in the Layered Oxide Superconductor<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>Ag</mml:mi><mml:mn>5</mml:mn></mml:msub><mml:msub><mml:mi>Pb</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>6</mml:mn></mml:msub></mml:math>

We measured the Fermi surface of the recently discovered superconductor Ag5Pb2O6 via a de Haas-van Alphen rotation study. Two frequency branches were observed and identified with the neck and belly orbits of a very simple, nearly free electron Fermi surface. We use the observed Fermi surface geometry to quantitatively deduce superconducting properties such as the in-plane and out-of-plane penetration depths, the coherence length in the clean limit, and the critical field; as well as normal state properties such as the specific heat and the resistivity anisotropy.

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“…Our dHvA experiment, reported in full in reference [6], revealed that the FS of Ag 5 Pb 2 O 6 is nearly free electron-like, as shown in Fig. 1.…”

Section: Experimental Fermi Surfacesupporting

confidence: 55%

Properties of the nearly free electron superconductor Ag5Pb2O6 inferred from Fermi surface measurements

Mann

Sutherland

Bergemann

et al. 2007

Physica C: Superconductivity and its Applications

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“…Indeed, in many metals, resistivity is found to saturate to a value close to ρ MIR at sufficiently high temperatures, in clear contrast to the prediction of ρ ∝ T based on the high-temperature Boltzmann theory. For Ag 5 Pb 2 O 6 , the MIR limit is estimated as ρ MIR ∼ 730 µΩcm, based on the values k F = 0.53 Å −1 determined from the quantum oscillation experiment 20,21 and d ∼ a = 5.93 Å. 18 Therefore, ρ c of Ag 5 Pb 2 O 6 is still smaller than the MIR limit in the present temperature range, manifesting the validity of semiclassical treatments of transport phenomena.…”

Section: A Resistivitymentioning

confidence: 69%

“…For B c, the orbital of the cyclotron motion is perpendicular to the c axis. Because the Fermi surface of Ag 5 Pb 2 O 6 is nearly axial-symmetric around the c * axis 19,20 (Fig. 1(c)), the cyclotron orbits are circles around the c * axis in k-space and v z (k(t)) is time-independent along each orbit.…”

Section: Magnetoresistancementioning

confidence: 99%

“…We discovered the ambient-pressure superconductivity of this oxide below T c = 52 mK by the resistivity and AC susceptibility measurements. 23,24 The band structure calculation 19 and the quantum oscillation experiment 20,21 revealed that Ag 5 Pb 2 O 6 has a nearly spherical "free-electron like" Fermi surface as shown in Fig. 1(c), despite its apparent layered structure.…”

Section: Introductionmentioning

confidence: 99%

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Transport properties of Ag5Pb2O6: A three-dimensional electron-gas-like system with low carrier density

Yonezawa

Maeno

2013

Phys. Rev. B

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We report normal-state transport properties of the single-crystalline samples of the silver-lead oxide superconductor Ag 5 Pb 2 O 6 , including the electrical resistivity, magnetoresistance, and Hall coefficient. From the Hall coefficient measurement, we confirmed that the carrier density of this oxide is as low as 5 × 10 21 cm −3 , one order of magnitude smaller than those for ordinary alkali metals and noble metals. The magnetoresistance behavior is well characterized by the axial symmetry of the Fermi surface and by a single relaxation time. The T 2 term of the resistivity is scaled with the specific heat coefficient, based on the recent theory for the electron-electron scattering. The present results provide evidence that Ag 5 Pb 2 O 6 is a low-carrier-density three-dimensional electron-gas-like system with enhanced electron-electron scatterings.

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“…Despite its low T c of 52.4 mK, 3 the material has attracted significant attention because of its nearly-free-electron nature in the normal metallic phase. 4,5 Typical nearly-free-electron materials, such as alkali and noble metals, do not exhibit superconductivity at ambient pressure, except Li, which has an extremely low T c of 0.4 mK. 6 Therefore, Ag 5 Pb 2 O 6 has been considered an ideal model system for investigating superconductivity without the effects of the complicated electronic structure.…”

Section: Introductionmentioning

confidence: 99%

Element-Specific Orbital Character in a Nearly-Free-Electron Superconductor Ag5Pb2O6 Revealed by Core-Level Photoemission

Sinn

Lee

Won

et al. 2017

Sci Rep

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Ag5Pb2O6 has attracted attentions due to its novel nearly-free-electron superconductivity, but its electronic structure and orbital character of the Cooper-pair electrons remain controversial. Here, we present a method utilizing core-level photoemission to show that Pb 6s electrons dominate near the Fermi level. We observe a strongly asymmetric Pb 4 f 7/2 core-level spectrum, while a Ag 3d 5/2 spectrum is well explained by two symmetric peaks. The asymmetry in the Pb 4 f 7/2 spectrum originates from the local attractive interaction between conducting Pb 6s electrons and a Pb 4 f 7/2 core hole, which implies a dominant Pb 6s contribution to the metallic conduction. In addition, the observed Pb 4 f 7/2 spectrum is not explained by the well-known Doniach-Šunjić lineshape for a simple metal. The spectrum is successfully generated by employing a Pb 6s partial density of states from local density approximation calculations, thus confirming the Pb 6s dominant character and free-electron-like density of states of Ag5Pb2O6.

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Nearly Free Electrons in the Layered Oxide SuperconductorAg5Pb2O6

Cited by 11 publications

References 27 publications

Properties of the nearly free electron superconductor Ag5Pb2O6 inferred from Fermi surface measurements

Properties of the nearly free electron superconductor Ag5Pb2O6 inferred from Fermi surface measurements

Transport properties of Ag5Pb2O6: A three-dimensional electron-gas-like system with low carrier density

Element-Specific Orbital Character in a Nearly-Free-Electron Superconductor Ag5Pb2O6 Revealed by Core-Level Photoemission

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