Tohoku University · 물리·천문학
Johan Åkerman 교수의 연구실은 스핀트로닉스 및 나노자기학 분야에서 핵심적인 연구를 수행하고 있습니다. 주요 연구 방향으로는 고온에서의 페로자성 전이 온도 향상, 자기 드롭렛 솔리톤의 실험적 관찰 및 제어, 그리고 스피너트론 기반 초고속 최적화 기술(이징 머신)의 구현이 있습니다. 또한 MRAM의 신뢰성 향상을 위한 터널 접합 및 메탈 인터커넥트의 내구성 평가도 중요한 연구 과제입니다.
표시된 성과는 수집된 데이터 기준으로 산출되며, 일부 차이가 있을 수 있습니다.
Enhancement of Curie temperature of gallium ferrite beyond room temperature by the formation of Ga 0.8 Fe 1.2 O 3 −Y 3 Fe 5 O 12 composite ,
Dissipative solitons have been reported in a wide range of nonlinear systems, but the observation of their magnetic analog has been experimentally challenging. Using spin transfer torque underneath a nanocontact on a magnetic thin film with perpendicular magnetic anisotropy (PMA), we have observed the generation of dissipative magnetic droplet solitons and report on their rich dynamical properties. Micromagnetic simulations identify a wide range of automodulation frequencies, including droplet o
Combinatorial optimization problems are known for being particularly hard to solve on traditional von Neumann architectures. This has led to the development of Ising Machines (IMs) based on quantum annealers and optical and electronic oscillators, demonstrating speed-ups compared to central processing unit (CPU) and graphics processing unit (GPU) algorithms. Spin torque nano-oscillators (STNOs) have shown GHz operating frequency, nanoscale size, and nanosecond turn-on time, which would allow the
The successful commercialization of MRAM will rely on providing customers with a robust and reliable memory product. The intrinsic reliability of magnetoresistive tunnel junction (MTJ) memory bits and the metal interconnect system of MRAM are two areas of great interest due to the new materials involved in this emerging technology. Time dependent dielectric breakdown (TDDB) and resistance drift were the two main failure mechanisms identified for intrinsic memory bit reliability. Results indicate
The bias and temperature dependent resistance and magnetoresistance of magnetic tunnel junctions with and without intentional shorts through the insulating barrier were studied. Based on the experimental results, a set of quality criteria was formulated that enables the identification of barrier shorts. While the temperature and bias dependencies of the junction resistance and of the fitted barrier parameters are very sensitive to the presence of such shorts, the same dependencies of the magneto
