Specific Heat of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msub><mrow><mi>YBa</mi></mrow><mrow><mn>2</mn></mrow></msub></mrow><mrow><msub><mrow><mi>Cu</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow><mrow><msub><mrow><mi>O</mi></mrow><mrow><mn>7</mn><mo>−</mo><mi>δ</mi></mrow></msub></mrow></math>, <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mn>0</mn><mi></mi><mi>≤</mi><mi></mi><mi mathvariant="italic">δ</mi><mi></mi><mi>≤</mi><mi></mi><mn>0.2</mn></math>: Concentrations of Paramagnetic Centers and Values of Other Parameters as Functions of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>δ</mi></math>

J. P. Emerson; D. A. Wright; B. F. Woodfield; J. E. Gordon; R. A. Fisher; N. E. Phillips

doi:10.1103/PhysRevLett.82.1546

Specific Heat of ${YBa}_{2} {Cu}_{3} O_{7 - δ}$ , $0 \leq δ \leq 0.2$ : Concentrations of Paramagnetic Centers and Values of Other Parameters as Functions of $δ$

J. P. Emerson, D. A. Wright, B. F. Woodfield, J. E. Gordon, R. A. Fisher, and N. E. Phillips

Phys. Rev. Lett. 82, 1546 – Published 15 February 1999

Abstract

The concentrations of paramagnetic centers and the values of other parameters, including the Debye temperature and the coefficient of the zero-field, temperature-proportional term, are reported as functions of $δ$ . The concentration of paramagnetic centers does increase with increasing $δ$ but, in striking contrast with the widely held expectation that the increase would be comparable to the increase in the concentration of O vacancies, it is as much as 2 orders of magnitude smaller. A new expression for the specific heat that takes into account the presence of spin-2 as well as spin- $\frac{1}{2}$ paramagnetic centers gives an accurate representation of the experimental data.

Received 23 March 1998

DOI:https://doi.org/10.1103/PhysRevLett.82.1546

Authors & Affiliations

J. P. Emerson, D. A. Wright, B. F. Woodfield^*, J. E. Gordon^†, R. A. Fisher, and N. E. Phillips

Department of Chemistry, University of California and Lawrence Berkeley National Laboratory, Berkeley, California 94720

^*Present address: Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602.
^†Permanent address: Department of Physics, Amherst College, Amherst, MA 01002.