I want to find the uses of Giant magnetoresistance (GMR) materials (not a GMR multilayers) over the Hall sensors to measure the magnetic fields between 1 Oe to 5 Tesla. Can GMR materials (Granular type) overcome the Hall sensors to measure the magnetic fields at room temperature (regarding performance and cost)?
What granular material you are planning to use? Most of the granular system shows low field magnetoresistance (for < 1Tesla field) arising from the grain boundary tunneling kind of mechanism. Also at the higher field range, CMR kind of mechanism is observed. If any material has coexistence of both (many materials have actually) then they can be useful for sensing small to large magnetic field. I think you should measure magnetoresistive response from the material in that field range and from calibration curve you can say what % change in resistance can arise from what external field. However, 1 Oe might be too small to sense accurately for such a sensor. But definitely you can try.
Thanks madam for your reply.
I want to know about the materials which are described by you as "granular systems" which gave MR at room temperature due to grain boundary tunneling. please refer me for some good reference for this case. Particularly, what are the granular composites those can show room temperature MR so that they could efficiently used as magnetic field sensors.
I have seen literature showing higher values of MR % (20-30 % at 5 T) in the intermetallic alloys. But, their higher MR values are reported around 4 K and hence they are not useful for room temperature applications. Hence, i want to know whether any kind of metallic alloys that show higher MR at room temperature due to their granular nature.
thanks again and looking forward to your reply.
Dear Venkatesh, I am not sure what granular material could be best for this purpose. I have experience with half metallic manganite LSMO and double perovskite oxide SFMO and both of them show MR at room temperature. Although the effect is maximum at low temperature. Also I have worked quite a lo with the thin films made from these materials and based on structural strains and grain boundaries the GB tunneling mechanism can be improved significantly. Actually a lot of room to play around in this area. You can have a look at this article and then we can discuss more: http://www.sciencedirect.com/science/article/pii/S0925838811019311
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