Tohoku University · 물리·천문학
미키히코 오오가네 교수의 연구실은 헤이즐러 합금 기반의 반도체 및 자기소재를 중심으로, 고감도 자기장 센서와 자기터널접합(MTJ) 소자의 개발에 중점을 두고 있습니다. 특히 Co₂MnSi, Co₂MnAl 등의 반완전도성 헤이즐러 합금의 에피택시 성장, 자기비대칭성 및 자기역학적 특성 제어, 그리고 초고감도 터널 자기저항(TMR) 센서를 활용한 심전도 및 핵자기공명 측정 기술을 연구하고 있습니다. 실험적 기술과 이론적 계산을 융합하여, 반도체적 자기소재의 전자구조와 자기감쇠 상수 간의 상관관계를 규명하고 있습니다.
표시된 성과는 수집된 데이터 기준으로 산출되며, 일부 차이가 있을 수 있습니다.
We determined the Gilbert damping constants of Fe–Co–Ni and Co–Fe–B alloys with various compositions and half-metallic Co2MnAl Heusler alloy films prepared by magnetron sputtering. The ferromagnetic resonance (FMR) technique was used to determine the damping constants of the prepared films. The out-of-plane angular dependences of the resonance field (HR) and line width (ΔHpp) of FMR spectra were measured and fitted using the Landau–Lifshitz–Gilbert (LLG) equation. The experimental results fitted
We fabricated B2-ordered Co2MnAl and L21-ordered Co2MnSi Heusler alloy films by optimizing various fabrication conditions (substrate, composition of sputtering target, substrate and post-annealing temperature, etc) and applied these films to bottom electrodes of magnetic tunnel junctions (MTJs). We used Al-oxide insulating tunnel barriers for our MTJs and varied oxidation times of Al films to control qualities of the Al-oxide insulating layer and Heusler-alloy/Al-oxide interface. Observed tunnel
Abstract We developed tunnel magneto-resistive (TMR) sensors based on magnetic tunnel junctions (MTJs) that are able to detect a weak, sub-pT, magnetic field at a low frequency. Small detectivities of 0.94 pT/Hz 1/2 at 1 Hz and 0.05 pT/Hz 1/2 at 1 kHz were achieved by lowering the resistance of MTJs and enhancement of the signal using a thick CoFeSiB layer and magnetic flux concentrators. We demonstrated real-time measurement of magnetocardiography (MCG) and nuclear magnetic resonance (NMR) of p
The magnetic damping constant in a series of Co2MnAlxSi1−x and Co2FexMn1−xSi Heusler alloy epitaxial films were systematically investigated by using ferromagnetic resonance technique. The determined magnetic damping constant is roughly proportional to the density of states at the Fermi energy of the first principle calculation. The result is consistent with the theoretical prediction when taking spin-orbit interaction into account. The small Gilbert damping constant for the fabricated films othe
Co 2 Fe Si films were prepared using magnetron sputtering technique on Cr buffer layers and MgO(001) substrates at various annealing temperatures. We investigated the crystal structures, magnetic properties (Ms and Hc), surface roughness, and magnetic damping constants (α) of the prepared Co2FeSi films. Out-of-plane angular dependences of the resonance field and the linewidth of the ferromagnetic resonance spectra were measured and fitted using the Landau-Lifshitz-Gilbert equation to determine t
