Calculation of the field and temperature dependence of thec-axis plasmon inBi2Sr2Ca2Cu2O8+δ

Abstract

We calculate the {ital c}-axis Josephson plasmon frequency {omega}{sub pl}(B,T) versus temperature {ital T} and magnetic induction {ital B} in Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 2}O{sub 8+{delta}}, treating the order parameter fluctuations in the lowest Landau level (LLL) approximation. The calculation agrees qualitatively with recent field-cooled measurements of Matsuda {ital et al.} assuming a {ital c}-axis dielectric constant {epsilon}{sub 0}{approximately}20{endash}50. For any given B, {omega}{sub pl} falls monotonically with increasing T, remains finite in the flux liquid state, and varies continuously across the solid-liquid transition when disorder is included. We also obtain an expression for {omega}{sub pl} which is valid everywhere in the flux liquid state and is not restricted to the LLL approximation. This expression leads to {omega}{sub pl}{approximately}1/{radical} (B) in the flux liquid state, in agreement with experiment. {copyright} {ital 1999} {ital The American Physical Society}