Lorenz number in the optimally doped and underdoped superconductor EuBa2Cu3Oy

M. Matusiak; Th. Wolf

doi:10.1103/PhysRevB.72.054508

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Lorenz number in the optimally doped and underdoped superconductor EuBa2Cu3Oy

M. Matusiak, Th. Wolf

DOI 10.1103/PhysRevB.72.054508 · Physical Review B

T1

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Abstract

The temperature dependences of the Hall-Lorenz numbers (Lxy) in a EuBa2Cu3Oy (Eu-123) single crystal before and after oxygen reduction are reported. The study is based on data on the normal state longitudinal and transversal transport coefficients. Namely, the temperature dependences of the electrical resistivity, Hall coefficient, longitudinal thermal conductivity, and transverse thermal conductivity are presented. The set of measurements was performed for an optimally doped sample (y≈7), then the oxygen content in the the same crystal was reduced to y≈6.65, and the measurements were repeated. For both cases Lxy’s are about two times larger than the Sommerfeld value of the Lorenz number and depend weakly on temperature in a range 300–160 K. Below T≈160K the Hall-Lorenz number for the optimally doped sample slowly drops, while the value of Lxy for the oxygen reduced sample begins to rise. Such results suggest that the electronic system in the investigated compound may be considered as a metallic one with pseudogaps that open at the Fermi level.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
EuBa2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	94.5	Pressure not reported	onset
EuBa2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	94	Pressure not reported	midpoint
EuBa2Cu3O7 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	94.5	Pressure not reported	onset
EuBa2Cu3O6.65 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	61	Pressure not reported	unknown
EuBa2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	62.5	Pressure not reported	unknown
YBa2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
(Pr,Ce)2CuO4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown