Probing the field-induced variation of the chemical potential in Bi(2)Sr(2)CaCu(2)O(y) via the magneto-thermopower measurements

TL;DR

This study investigates how the chemical potential in Bi(2)Sr(2)CaCu(2)O(y) varies with magnetic field by analyzing magneto-thermopower measurements and incorporating field-dependent chemical potential into Ginzburg-Landau theory.

Contribution

The paper introduces a field-dependent chemical potential into Ginzburg-Landau theory to explain asymmetries in magneto-thermopower data near the critical temperature.

Findings

Field-induced variation of chemical potential is proportional to the magneto-thermopower peak.

Asymmetry in thermopower is explained by field-dependent chemical potential.

Simple relationship established between chemical potential variation and thermopower data.

Abstract

Approximating the shape of the measured in $Bi_2Sr_2CaCu_2O_y$ magneto-thermopower (TEP) $\Delta S(T,H)$ by asymmetric linear triangle of the form $\Delta S(T,H)\simeq S_p(H)\pm B^{\pm}(H)(T_c-T)$ with positive $B ^{-}(H)$ and $B ^{+}(H)$ defined below and above $T_c$, we observe that $B ^{+}(H)\simeq 2B ^{-}(H)$. In order to account for this asymmetry, we explicitly introduce the field-dependent chemical potential of holes $\mu (H)$ into the Ginzburg-Landau theory and calculate both an average $\Delta S_{av}(T,H)$ and fluctuation $\Delta S_{fl}(T,H)$ contributions to the total magneto-TEP $\Delta S(T,H)$. As a result, we find a rather simple relationship between the field-induced variation of the chemical potential in this material and the above-mentioned magneto-TEP data around $T_c$, viz. $\Delta \mu (H)\propto S_p(H)$.