The electronic specific heat of over and underdoped Y0.9Ca0.1Ba2Cu3O6+x

doi:10.1016/0921-4534(94)92089-3

Physica C: Superconductivity

Volumes 235–240, Part 3, December 1994, Pages 1735-1736

https://doi.org/10.1016/0921-4534(94)92089-3 Get rights and content

Abstract

The electronic specific heat coefficient γ(T) of Y_0.9Ca_0.1Ba₂Cu₃O_6+x has been determined between 1.8K and 300K as a function of x. Ca substitution for Y increases the planar hole concentration, overdoping the fully oxygenated material and lowering x_opt for optimum T_c to 0.78 for 10% Ca doping. A dramatic collapse of the specific heat jump for x<0.86 provides clear evidence for the opening of a normal state pseudogap in the underdoped material. From the shift to lower x by ∼0.1 relative to corresponding values for YBa₂Cu₃O_6+x we conclude that both x_opt and the onset of a pseudogap are determined by the planar hole concentration and not decoupling of the planes or chain disorder due to oxygen vacancies.

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The electronic specific heat of over and underdoped Y0.9Ca0.1Ba2Cu3O6+x

Abstract

Phys. Rev. Letts.

Journal of Superconductivity

The electronic specific heat of over and underdoped Y_0.9Ca_0.1Ba₂Cu₃O_6+x