This paper focus on the development of a single portable roadside magnetic sensor for vehicle classification. The magnetic sensor is a kind of anisotropic magnetic device that do not require to be embedded in the roadway-the device is placed next to the roadway and measure traffic in the immediately adjacent lane. A novel feature extraction and comparison approach is presented for vehicle classification with a single magnetic sensor, which is based on four different feature sets extracted from the detected magnetic signal. Furthermore, vehicle classification has been achieved with three common classification algorithms, including support vector machine, k-nearest neighbors and back-propagation neural network. Experimental results have demonstrated that the Peak-Peak feature set with back-propagation neural network approach performs much better than other approaches. Besides, the normalization technology has been proved it does work.

In this paper, we have succeeded in the fabrication of high performance Magnetic Tunnel Junction (MTJ) which is integrated in CMOS circuit with 4-Metal/ 1-poly Gate 0.14 µm CMOS process. We have measured the DC characteristics of the MTJ that is fabricated on via metal of 3rd layer metal line. This MTJ of 60180 nm2 achieves a large change in resistance of 3.52 kΩ (anti-parallel) with TMR ratio of 151% at room temperature, which is large enough for sensing scheme of standard CMOS logic. Furthermore, the write current is 320 µA that can be driven by a standard MOS transistor. As the results, it is shown that the DC performance of our fabricated MTJ integrated in CMOS circuits is very good for our novel spin logic (MTJ-based logic) device.

A three-dimensional micromagnetic simulation using the Landau-Lifshitz-Gilbert equation was performed for thin-film magnetic recording media and magnetoresistive (MR) heads with soft adjacent layers (SAL). For recording media the simulation results for magnetization curves and media noise were compared with the results of experiments. Although the media model needs to be improved, the qualitative agreement between simulation results and experimental results shows that this micromagnetic simulation can be a useful tool for analyzing and predicting magnetic properties and recording characteristics. This work also showed that media noise is influenced by magnetostatic interaction, and that the decrease of the magnetostatic interaction is favorable for obtaining a high signal-to-noise ratio. For an MR head the output obtained with a nonuniform sense current distribution is similar to the output obtained with uniform sense current distribution for both low and high anisotropy fields (Hk=2 Oe and 10 Oe) SAL. With the low Hk SAL, however, the asymmetry of the output obtained for nonuniform sense current differs from the asymmetry obtained for uniform sense current; the difference is due to a magnetization vortex in a biased state in the SAL. With the high Hk SAL, the difference between the asymmetry obtained for nonuniform sense current and the one obtained for uniform sense current is not large; no vortices are found in the SAL at the biased state.

We have fabricated a thin head composed of a double layer magnetoresistive (MR) reproducing element and an inductive recording element for high density rigid disk drives. We have also developed a low noise reproducing amplifier IC whose input noise level is 0.3nV/Hz. Our experimental results indicate that equal electrical potential between the exposed area of the MR element and the medium's surface improves the durability of our MR head.