Differential type Scanning Hall probe microscopy with high resolution of magnetic field image

研制了一种能在20 ~ 300 K温度范围内，在15 kOe以下的外磁场中工作的扫描霍尔探针显微镜。在低温恒温器中安装扫描探头和载物台，扫描探头和载物台置于产生15 kOe磁场的电磁铁的差距中，测量薄膜表面磁场图像随垂直于铁磁薄膜平面的外磁场的变化，并减去外磁场的贡献，得到薄膜上方的杂散磁场图像。扫描平台采用非磁性不锈钢和蓝宝石滚珠轴承，避免了扫描装置的磁致伸缩。载物台由步进电机和压电致动器控制，它们放置在低温恒温器外部并远离所施加的磁场。研制了一种比传统GaAs/AlGaAs探针更耐用的Si-MOSFET微霍尔探针（SHPM）。该探针的霍耳系数在室温下为0.18 Ω/G，可用于本研究所研制的SHPM。

A scanning Hall probe microscope, which can be used in external magnetic fields below 15 kOe in the temperature range from 20 K to 300K, is developed. The surface magnetic images are measured as a function external magnetic field perpendicular to a ferromagnetic film plane, and the stray-magnetic-field images above the film are obtained by subtracting the external magnetic filed contributions.A scanning probe and stage are installed in a cryostat which is set in the gap of an electromagnet generating magnetic fields up to 15 kOe. The scanning stage is made of non-magnetic stainless and sapphire ball bearing in order to avoid magnetostriction of the scanning devices. The stage is controlled by stepping motors and piezo actuators which are placed outside the cryostat and flee from the applied magnetic field. The active scanning area is 2mm x 2mm and the spatial resolution is 0.5μgm.A Si-MOSFET micro-Hall probe (SHPM), which is more durable than conventional GaAs/AlGaAs probe, was developed. The Hall coefficient of the Si-MOSFET probe, is 0.18 Ω/G at room temperature, being adequate to use in the SHPM developed in the present study.