Pseudogap in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>Bi</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>Sr</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>CaCu</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi>O</mml:mi></mml:mrow><mml:mrow><mml:mn>8</mml:mn><mml:mo>+</mml:mo><mml:mi>δ</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>Studied by Measuring Anisotropic Susceptibilities and Out-of-Plane Transport

We find in the ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+\ensuremath{\delta}}$ system that the characteristic temperatures ${T}_{\ensuremath{\chi}}^{*}$ [below which the uniform susceptibilities ${\ensuremath{\chi}}_{\mathrm{ab}}(T)$ $(H\ensuremath{\perp}c)$ and ${\ensuremath{\chi}}_{c}(T)$ $(H\ensuremath{\parallel}c)$ decrease] and ${T}_{{\ensuremath{\rho}}_{c}}^{*}$ [below which the out-of-plane resistivity ${\ensuremath{\rho}}_{c}(T)$ shows typical upturn] coincide for all doping levels. We attribute the $T$ dependence of $\ensuremath{\chi}$'s and ${\ensuremath{\rho}}_{c}$ to the anomalous (pseudogapped) density of states (DOS) in high- ${T}_{c}$ cuprates. Furthermore, the anisotropy in the $T$ dependence of $\ensuremath{\chi}$'s is universal, i.e., ${\ensuremath{\chi}}_{c}\ensuremath{\propto}1.6{\ensuremath{\chi}}_{\mathrm{ab}}$, showing that there is only a single $T$-dependent component in the $\ensuremath{\chi}$'s. This implies that the Curie-like behavior ( $d\ensuremath{\chi}/\mathrm{dT}&lt;0$) observed in overdoped samples is also caused by a DOS effect.

Перевод пока недоступен