Probing the field-induced variation of the chemical potential in Bi2Sr2CaCu2Oy via magneto-thermopower measurements

Approximating the shape of the magneto-thermoelectric power (TEP) Delta S(T ,H) measured in Bi2Sr2CaCu2Oy by an asymmetric linear triangle of the form Delta S(T,H)similar or equal to S-p(H)+/- B+/-(H)(T-c-T) with positive B-(H ) and B+(H) defined below and above T-c, we observe that B+(H)similar or eq ual to 2B(-)(H). To account for this asymmetry, we explicitly introduce the field-dependent chemical potential mu(H) of holes into the Ginzburg-Landau theory and calculate both an average Delta S-av(T,H) and fluctuation contr ibution Delta S-fl(T,H) to the total magneto-TEP Delta S(T,H). As a result, we find a rather simple relationship between the field-induced variation o f the chemical potential in this material and the above-mentioned magneto-T EP data around T-c, viz. Delta mu(H)proportional to S-p(H). (C) 1999 Americ an Institute of Physics. [S1063-7761(99)01807-7].