Effect of flux pinning on the Nernst and Ettingshausen effects in high-Tc superconductors

Theoretical expressions for the Nernst and Ettingshausen coefficients in high-T-c cuprate superconductors are derived by taking account of the effects of flux pinning. It is shown that these coefficients are essentially subjected by the flux pinning characteristics of the sample even above the glass liquid transition temperature, T-GL, where the observed values of these coefficients become dominant. While the existing observed data are not sufficient for carrying out the quantitative comparison with the present theory because of the lack of the description on the detailed pinning characteristics of the observed sample, a preliminary comparison with the existing observed data showed a semi-quantitative agreement under the choice of reasonable values for the pinning characteristics of the sample, except in the vicinity of the critical temperature where the fluctuating appearance of superconductivity cannot be neglected. Then the present theory can be a target of the quantitative comparison with future detailed measurements. (C) 1999 Elsevier Science B.V. All rights reserved.