关于MgB_2/Al_2O_3超导薄膜电阻转变和各向异性的研究  

A study on resistive transition and anisotropy of MgB_2/Al_2O_3 superconducting thin films

作　　者：史力斌[1] 任骏原[1] 张凤云[1] 张国华[2] 余增强[3] 

机构地区：[1]渤海大学物理系,锦州121000 [2]北京科技大学应用科学学院物理系,北京100083 [3]北京大学物理学院,北京100871

出　　处：《物理学报》2007年第9期5353-5358,共6页Acta Physica Sinica

基　　金：国家自然科学资金(批准号:10174006)资助的课题.~~

摘　　要：利用电子束蒸发方法将MgB2超导薄膜沉积到Al2O3(001)衬底上.采用标准的四引线法研究了磁场平行和垂直超导薄膜ab平面下的电阻转变.一个激活能模型U(T,H)=U0(1-T/(Tc+δ))n(1-H/Hc2(0))m被建立用来分析超导薄膜磁通线的激活能和电阻转变,结果表明该模型能够在整个转变温度范围描述超导体磁通线的激活能和电阻转变.另外,利用多项式Hc2(t)=Hc2(0)+At+Bt2分析了MgB2/Al2O3超导薄膜的上临界磁场,获得了该超导薄膜的各向异性参数γ=Hc2ab(0)/Hc2c(0)=2.26.MgB2 thin films were deposited by e-beam on Al2O3（001）substrates. Resistive transition of the MgB2/Al2O3 was investigated in different magnetic fields applied parallel or perpendicular to the ab plane of the films by the standard four-probe method. An activation energy model is suggested to analyze quantitatively the activation energy of flux lines and resistive transition in whole transition temperature range. The anisotropy parameter γ= H c2 ^ab （0）/H c2^ c（0） =2.26 was obtained by analyzing the upper critical field using the polynomial H c2 （t）= H c2 （0）＋At＋Bt^2.

关 键 词：MgB2/Al2O3 超导体 电阻转变 各向异性 

分 类 号：O484.42[理学—固体物理] O511[理学—物理]