Thermodynamics and critical fields of YBa{sub 2}(Cu{sub 1{minus}{ital x}}Ni{sub {ital x}}){sub 3}O{sub 7{minus}{delta}} from a {ital d}-wave model of superconductivity
- Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States)
Specific heat, penetration depth, and infrared measurements on Ni- and Zn-doped YBa{sub 2}(Cu{sub 1{minus}{ital x}}{ital M}{sub {ital x}}){sub 3}O{sub 7{minus}{delta}} are shown to be consistent with each other within the framework of a phenomenological model in which a {ital d}-wave density of states is broadened by the disorder associated with the dopant. Strong scattering from each dopant atom results in a rapid filling in of the low-energy density of states. We use the model, with scattering rates taken from the infrared reflectance and a normal-state density of states taken from the specific heat, to calculate the thermodynamic critical field {ital H}{sub {ital c}}({ital T}), the specific heat {ital C}({ital T}), the {ital ab}-plane penetration depth {lambda}({ital T}), the {ital ab}-plane coherence length {xi}({ital T}), and the critical fields {ital H}{sub {ital c}1}({ital T}) and {ital H}{sub {ital c}2}({ital T}) for fields applied perpendicular to the {ital ab} plane. {ital C}({ital T}) and {lambda}({ital T}) are compared, favorably, with measurements. {xi} and {ital H}{sub {ital c}2} have not been measured directly, so this paper presents the first experimental estimate of these quantities. It is found that {xi}(0) increases by less than 50{percent} with increasing Ni concentration, even though the superfluid density, proportional to 1/{lambda}{sup 2}(0), decreases by a factor of 10. {copyright} {ital 1996 The American Physical Society.}
- Research Organization:
- Purdue Univ., West Lafayette, IN (United States)
- DOE Contract Number:
- FG02-90ER45427
- OSTI ID:
- 286130
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 53, Issue 17; Other Information: PBD: May 1996
- Country of Publication:
- United States
- Language:
- English
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