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本本文报道了基于混合物理化学气相沉积方法制备高质量干净极限MgB2薄膜和碳掺杂MgB2薄膜的最新结果。c轴外延干净的MgB2薄膜具有高达41.4K的超导转变温度,低于0.3μΩcm的正常态剩余电阻率,样品处于干净极限。薄膜表面RMS粗糙度小于5nm,在150nm宽的纳桥上测量到了大于1×108A/cm2的临界电流密度,接近MgB2材料理论上的拆对电流密度,同样的结果也从对相同样品的磁性测量中推导得到。利用甲烷作为碳源,基于改进的热丝辅助混合物理化学气相沉积装置,高性能碳掺杂MgB2薄膜得以成功实现。不同程度的碳掺杂调制了MgB2双能带的带内和带间散射,进而明显增强了薄膜的上临界场。在重碳掺杂MgB2薄膜样品中,平行于样品表面的上临界场分量,Hc2//ab在临界温度(27K)附近对温度的斜率,-dHc2//ab/dT达到了3T/K,暗示了样品具有非常高的上临界场Hc2//ab(0)。碳掺杂同时使得样品的磁通钉扎能力得到很大增强,高场下具有比干净样品高出数个量级的临界电流密度,和更高的不可逆场。
This paper reports the latest results of the preparation of high quality clean-limit MgB2 thin films and carbon-doped MgB2 thin films based on hybrid physical and chemical vapor deposition. The c-axis epitaxy clean MgB2 film has a superconducting transition temperature of up to 41.4K, a normal residual resistivity of less than 0.3μΩcm, and the sample is at the clean limit. The RMS roughness of the film surface is less than 5 nm. The critical current density of more than 1 × 10 8 A / cm 2 is measured on a 150 nm wide nanocapillary bridge, which is close to the theoretical split pair current density of MgB2. The same result is obtained from the magnetic measurements Derived. Using methane as a carbon source, a high-performance carbon-doped MgB2 thin film was successfully achieved based on an improved hot wire assisted hybrid physical chemical vapor deposition apparatus. Different degrees of carbon doping modulate the in-band and inter-band scattering of the MgB2 dual band, which in turn significantly enhances the upper critical field of the film. In heavy carbon-doped MgB2 film samples, the slope of the Hc2 // ab near the critical temperature (27K) to the temperature, -dHc2 // ab / dT, reached 3T / K parallel to the upper critical field component of the sample surface, suggesting that The sample has a very high upper critical field Hc2 // ab (0). Carbon doping also greatly enhances the flux pinning capability of the samples, with several orders of magnitude higher critical current densities and higher irreversible fields in the high field.