Fluctuational ettingshausen effect in single crystals of YBa₂Cu₃O_7-δ

We have studied the Ettingshausen effect in single crystals of YBa₂Cu₃O_7-δ near the superconducting transition temperature T_c. Two distinct regimes were found in the field dependence of the Ettingshausen coefficient - a low-field regime where flux-flow dominates and a high-field regime where fluctuation dominates. The result is in agreement with Ullah and Dorsey's scaling theory for fluctuational Ettingshausen effect, and seems also consistent with Maki's mean-field theory when the temperature of the sample is several Kelvins away from T_c.