• Recently, many tunnel magnetoresistance devices with high magnetoresistance effect are reported. These are expected to be applied to high sensitive magnetic sensors. There are many magnetic sensors with variety of the mechanism, in order to meet the demand of the very wide range of sensing magnetic field. However, there is no magnetic sensor which has high sensitivity, easy to use, operation at room temperature and low cost. Only a magnetic sensor with tunnel magnetoresistance devices can satisfy all the demand in principle. As the device has very wide range of the sensing magnetic field, it can be designed for any demand to the sensors.

For example, this device can sense a bio-magnetic field easily at room temperature, so that it could be replaced SQUID device, which is popular now but is very expensive and not easy to use personally. Therefore, by using this device, we expect we can conduct effective collaborative research in medical field.

• Highly-sensitive NMR technique has been developed by manipulation polarization of nuclear spins via control of transport characteristics in GaAs and InSb quantum structures. This highly-sensitive NMR can be applied to two-dimensional and nanostructures. Furthermore, ideal gate controllability has been demonstrated in InSb quantum structures with Al2 O3 dielectrics. More importantly, the concept of generalized coherence time was introduced, where noise characteristics felt by nuclear spins can be measured including their frequency dependence. This concept will bring about a change in all nuclear-spin related measurements.

Next generation InSb devices based on good gate controllability. Various nuclear-spin based measurements and NMR utilizing the concept of generalized coherence time. Highly-sensitive NMR is now important for fundamental physics studies. In the future, it will contribute to quantum information processing.