Katsumichi Tagami

Electrical Spin Injection into Silicon Using MgO Tunnel Barrier

We demonstrate the evidence of electrical spin injection into silicon (Si) using the Fe/MgO tunnel barrier by the following two methods: 1) non-local (NL) four-terminal magnetoresistance (MR) scheme with their respective corresponding ferromagnetic (FM) electrode and 2) Hanle-type spin precession scheme. These results are compatible and in agreement with each other. The spin injection signals in the non-local scheme were observed up to 150 K, and the spin diffusion length (¿N) was estimated to be 2.8 ¿m at 8 K. The experimental data completely matches every detail of the Hanle measurements equation, and spin lifetime (¿) was estimated to be 9.44 ns at 8 K. We will be able to discuss the physical properties of a pure spin current in silicon by this compelling data.

Transport and Magnetic Properties of CPP-GMR Sensor With CoMnSi Heusler Alloy

We investigated structural and magnetic properties of CoMnSi (CMS) Heusler alloy films and giant magneto-resistance (GMR) ratio of current-perpendicular-to-plane (CPP) GMR sensor elements. The films were deposited with magnetron sputtering method and annealed at 673 K and 773 K. The CMS films were identified as B2 structure by using X-ray diffraction and the magnetization of the films were evaluated as 0.95 T. We fabricated the CPP-GMR sensors varying the composition of the CMS films, Co48 Mn21 Si31 (at. %) as Si-rich CMS and Co51Mn25Si24 (at. %) as CMS-ref, having a FeCo layer between the CMS and Cu spacer. It was found that the element with Si-rich CMS exhibited higher GMR ratio of 9.0% than that with CMS-ref. Our calculations indicate that larger spin polarization of contact region between the CMS film and the FeCo film relates to larger GMR ratio.

Performance of Discrete Track Perpendicular Media on Off-Track-Capability at Higher Track Density

The off-track-capability (OTC) of the discrete track perpendicular medium is investigated by using Landau-Lifshitz-Gilbert micromagnetic simulation. The OTC is very important to design the system of the HDD. In this simulation, the OTC of the read head, the OTC of the write head and the OTC where both the read head and the write head have off-track are shown from the point of signal-to-noise ratio (SNR). The simulation results show that the discrete track medium has superior advantage on the OTC for both reading and writing process