Development of Low Temperature Scanning Tunneling/Magnetic Force Microscope to Observe Magnetic Flux Lattice in High Temperature Superconductor

煎饼理论是描述高温超导体中磁通量行为的著名理论之一，它预测了高温超导体中磁通量周围涡-反涡对的形成。研制了能探测磁场的低温扫描隧道显微镜，以观察高温超导体中预测的涡-反涡对。在项目的第一年，我们做了(1)超导体中MFM悬臂梁与磁通量相互作用的理论研究。确定了MFM检测磁通量的适宜条件。(2)研制了低温扫描隧道显微镜。在项目的第二年（即项目的最后一年），将低温扫描隧道显微镜改进为低温原子力显微镜，得到了液氦和液氮温度下材料表面拓扑的初步结果。开发了一种新的悬臂梁弯曲检测机构，该机构可以在任何温度下工作。(2)几种可检测各种力的悬臂梁，如磁力、静电场、侧向力等，以测试所研制仪器的性能。

The Pancake theory that is one of the famous theory to describe the behavior of the magnetic flux in a high temperature superconductor predicts the formation of the vortex-antivortex pair around the magnetic flux in the high temperature superconductor. We develop the low temperature scanning tunneling microscope which can detect the magnetic force to observe the predicted vortex-antivortex pair in the high temperature superconductor.In the first year of the project, we did(1) Theoretical research of the interaction between the cantilever of MFM and a magnetic flux in a superconductor. The appropriate condition to detect the magnetic flux by MFM was determined.(2) The low temperature scanning tunneling microscope was developed. The apparatus give the preliminary results of the surface topology of the materials at liquid helium and liquid nitrogen temperatureIn the second year of the project (i.e., the last year of the project)(1) The low temperature scanning tunneling microscope was modified to low temperature atomic force microscope. A new mechanism was developed to detect the bending of the cantilever, which can work at any temperature.(2) Several types of cantilevers which can detect variety of force, i.e., magnetic force, static electric field, lateral force, etc. : to test the performance of the developed apparatus.