The original motivation for construction of an AGFM has been detailed in section 1.2.1, resulting in a target resolution of 10-8 J T-1 kg-1 or better. It was decided to initially develop the instrument for ambient temperature operation, with a view to subsequently extending operation to cryogenic temperatures. This enabled initial characterisation of the instrument (reported in chapter 3), without the expense of a cryogen supply. Once a room temperature system was established, adaptation to enable measurements down to 77 K was attempted. Cost was also a major influence in many of the design decisions taken, with a limited budget available for development work. The Hg1-xMnxTe film samples available were ~0.5 mm thick (including substrate), between 3 and 10 mm across, and were all less than 0.3 grams in weight. The AGFM was therefore designed to accommodate such samples. A conventional iron yoke electromagnet was used, capable of generating homogenous fields up to 400 mT. A schematic of the AGFM is shown in Figure 2.2.
2.2.1
The original motivation for construction of an AGFM has been detailed in section 1.2.1, resulting in a target resolution of 10-8 J T-1 kg-1 or better. It was decided to initially develop the instrument for ambient temperature operation, with a view to subsequently extending operation to cryogenic temperatures. This enabled initial characterisation of the instrument (reported in chapter 3), without the expense of a cryogen supply. Once a room temperature system was established, adaptation to enable measurements down to 77 K was attempted. Cost was also a major influence in many of the design decisions taken, with a limited budget available for development work. The Hg1-xMnxTe film samples available were ~0.5 mm thick (including substrate), between 3 and 10 mm across, and were all less than 0.3 grams in weight. The AGFM was therefore designed to accommodate such samples. A conventional iron yoke electromagnet was used, capable of generating homogenous fields up to 400 mT. A schematic of the AGFM is shown in Figure 2.2.
2.2.1
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