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Scanning Hall probe microscope (SHPM) is a variety of a scanning probe microscope which incorporates accurate sample approach and positioning of the scanning tunnelling microscope with a semiconductor Hall sensor. This combination allows to map the magnetic induction associated with a sample. Current state of the art SHPM systems utilize 2D electron gas materials (e.g. GaAs/AlGaAs) to provide high spatial resolution (~300 nm) imaging with high magnetic field sensitivity. Unlike the magnetic force microscope the SHPM provides direct quantitative information on the magnetic state of a material. The SHPM can also image magnetic induction under applied fields up to ~1 tesla and over a wide range of temperatures (millikelvins to 300 K). The SHPM can be used to image many types of magnetic structures. A few structures are listed below. *Thin films *Permanent Magnets. *MEMS structures. *Current carrying traces on PCBs *Permalloy disks *Recording media Advantages to other magnetic raster scanning methods SHPM is a superior magnetic imaging technique due to many reasons including: : *Unlike the MFM technique, the Hall probe exerts negligible force on the underlying magnetic structure and is noninvasive. : *Unlike the magnetic decoration technique, the same area can be scanned over and over again. : *Magnetic field caused by hall probe is so minimal it has a negligible effect on sample it is measuring. : *Sample does not need to be an electrical conductor, unless using STM for height control. : *Measurement can be performed from 5 - 500 K. : *Measurement can be performed in ultra high vacuum (UHV). : *Measurement is nondestructive to the crystal lattice or structure. : *Tests requires no special surface preparation or coating. : *Detectable magnetic field sensitivity, is approximately 0.1 uT - 10 T. : *SHPM can be combined with other scanning methods like STM. Limitations There are some shortcomings or difficulties when working with an SHPM, and some of these are as follows: : *High resolution scans become difficult due to the thermal noise of extremely small hall probes. : *There is a minimum scanning height distance due to the construction of the hall probe. (This is especially significant with 2DEG semi-conductor probes due to there multi-layer design). : *Scanning (lift) height affects obtained image. : *Scanning large areas takes a significant amount of time. : *Relatively short practical scanning range (order of 1000's micrometer) along any direction. : *Housing is important to shield electromagnetic noise (Faraday cage), acoustic noise (anti-vibrating tables), air flow (air isolation cupboard), and static charge on the sample (ionizing units). ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Scanning Hall probe microscope」の詳細全文を読む スポンサード リンク
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