YBa_2Cu_3O_(7-δ)外延膜中的非线性光响应  

NONLINEAR OPTICAL RESPONSE OF EPITAXIAL YBa_2Cu_3O7-δ FILMS

作　　者：徐克西[1] 周世平 鲍家善[1] 

机构地区：[1]上海大学物理系

出　　处：《物理学报》1998年第2期307-315,共9页Acta Physica Sinica

基　　金：上海市教育委员会曙光计划资助的课题

摘　　要：实验结果表明，在连续波ＨｅＮｅ激光（λ＝０６３μｍ）照射下，ＹＢａ２Ｃｕ３Ｏ７－δ（ＹＢＣＯ）外延膜在超导转变温度Ｔｃ以下附近温区的光响应行为，表现为辐射热效应和非辐射热效应同时存在，尤其当样品的ＲＴ变化率ｄＲ／ｄＴ→０温区明显地表现为一种非平衡光响应行为，且随电流的变化呈非线性关系．基于上述实验事实，在光致准粒子激发假设下，对Ｔｃ附近ＹＢＣＯ薄膜中的非线性光响应机制进行了讨论；给出了光辐射作用下超导体自由能密度增量表达式；提出了有关ＹＢＣＯ外延膜中的光激发损耗，可能主要源于光致准粒子激发和磁通涡旋运动所诱发的超导序参量相位变化的观点．分析结果还表明，这种非线性光响应机制很可能与不可逆线机制或电阻转变展宽机制有关联．Abstract Experiments showed that the non equiliubrium optical response of epitaxial YBa_ 2Cu _3O7-δ films below T c existed with the illumination of He Ne laser (λ=063μm). We have also found that near the transition region, where dR/dT is vanishing, the optical response becomes a strong nonlinear functions of current. A model was presented to explain the mechanism of the nonlinear behavior based on the interactions between photoexcited quasiparticles and the vortex in high T c superconductor. We believe that the mechanism of the dissipation induced by light illumination in transition region may be correlated with the mechanism of “irreversibility line” or that of “broaden resistive transition” in magnetic fields.

关 键 词：YBCO 外延 非线性光响应 高TC 

分 类 号：TM263.014[一般工业技术—材料科学与工程]