• Title/Summary/Keyword: spin transfer

Search Result 213, Processing Time 0.034 seconds

Technology Trend of Spin-Transfer-Torque Magnetoresistive Random Access Memory (STT-MRAM) (스핀전달토크형 자기저항메모리(STT-MRAM) 기술개발 동향)

  • Kim, D.K.;Cho, J.U.;Noh, S.J.;Kim, Y.K.
    • Journal of the Korean Magnetics Society
    • /
    • v.19 no.1
    • /
    • pp.22-27
    • /
    • 2009
  • Reduction of the critical current density ($J_c$) for STT magnetization switching is most important issue of magnetic tunnel junctions (MTJs) based MRAM. This report describes how to decrease the Jc and will introduce the recent research progresses of STT-MRAM devices with material engineering and structural improvement, respectively.

SI-BASED MAGNETIC TUNNELING TRANSISTOR WITH HIGH TRANSFER RATIO

  • S. H. Jang;Lee, J. H.;T. Kang;Kim, K. Y.
    • Proceedings of the Korean Magnestics Society Conference
    • /
    • 2003.06a
    • /
    • pp.24-24
    • /
    • 2003
  • Metallic magnetoelectronic devices have studied intensively and extensively for last decade because of the scientific interest as well as great technological importance. Recently, the scientific activity in spintronics field is extending to the hybrid devices using ferromagnetic/semiconductor heterostructures and to new ferromagnetic semiconductor materials for future devices. In case of the hybrid device, conductivity mismatch problem for metal/semiconductor interface will be able to circumvent when the device operates in ballistic regime. In this respect, spin-valve transistor, first reported by Monsma, is based on spin dependent transport of hot electrons rather than electron near the Fermi energy. Although the spin-valve transistor showed large magnetocurrent ratio more than 300%, but low transfer ratio of the order of 10$\^$-5/ prevents the potential applications. In order to enhance the collector current, we have prepared magnetic tunneling transistor (MTT) with single ferromagnetic base on Si(100) collector by magnetron sputtering process. We have changed the resistance of tunneling emitter and the thickness of baser layer in the MTT structure to increase collector current. The high transfer ratio of 10$\^$-4/ range at bias voltage of more than 1.8 V, collector current of near l ${\mu}$A, and magnetocurrent ratio or 55% in Si-based MTT are obtained at 77K. These results suggest a promising candidate for future spintronic applications.

  • PDF

Study on a Spin Stabilization Technique Using a Spin Table (스핀테이블을 이용한 스핀안정화 기법 연구)

  • Kim, Dae-Yeon;Suh, Jong-Eun;Han, Jae-Hung;Seo, Sang-Hyeon;Kim, Kwang-Soo
    • Journal of the Korean Society for Aeronautical & Space Sciences
    • /
    • v.46 no.5
    • /
    • pp.419-426
    • /
    • 2018
  • For an orbit transfer in a space exploration mission, a solid or liquid rocket booster is included at the last stage of the launch vehicle. During the orbit transfer, thrust misalignment can cause a severe orbit error. Three axis attitude control or spin stabilization can be implemented to minimize the error. Spin stabilization technique has advantages in structural simplicity and lightness. One of ways to apply the spin stabilization to the payload is to include a spin table system in the launch vehicle. In this paper, effect of the spin table system on separation dynamics of the payload is analyzed. Simple model of the spin table to mimic basic functions is designed and simulation environment is established with the model. Effect of the spin table is tested by evaluating separation dynamics of a payload with and without the spin table. Analysis on tolerance effect of separation spring constant on separation dynamics of a payload is conducted.

SPIN POLARIZED PHOTOEMISSION AND MAGNETIC CIRCULAY DICHROISM STUDY OF FeAl THIN FILMS

  • Kim, K.W.;Kudryavtsev, Y.V.;Chang, G.S.;Whang, C.N.;Lee, Y.P.
    • Journal of the Korean Vacuum Society
    • /
    • v.6 no.S1
    • /
    • pp.53-58
    • /
    • 1997
  • It is well known that the equiatomic FeAl alloy crystallizes in a paramagnetic CsCl structure and is very stable in a wide temperature range owing to a significant charge transfer from Al to Fe. A presence of structural defects normally enhances the magnetic and magneto-optical properties of this alloy. In this study spin-resolved photoemission and magnetic circular dichroism (MCD) were carried out on both ordered and disordered $Fe_{0.52}Al_{0.48}$ alloy films. The disordered state in the alloy films was obtained by a vapor quenching deposition on cooled substrates. It is shown that the order-disorder transition in the Fe0.52Al0.48 alloy films leads to a significant change in the spin polarization. Form the MCD results the orbital and spin magnetic moments of the constituent atoms are obtained. According to the sum rule the spin and orbital magnetic moments of Fe in the disordered FeAl film are $\mu\frac{SR}{spin}=0.8\mu_B$ and $\mu\frac{SR}{orb}=0.14\mu_B$ respectively. The spin magnetic moment is also evaluated to be $\mu\frac{BR}{spin}=0.77\mu_B$ by the branching ration method employing a photon polarization of 90%.

  • PDF

Spin Torque Nano-Oscillator with an Exchange-Biased Free Rotating Layer

  • You, Chun-Yeol
    • Journal of Magnetics
    • /
    • v.14 no.4
    • /
    • pp.168-171
    • /
    • 2009
  • We propose a new type of spin torque nano-oscillator structure with an exchange- biased free rotating layer. The proposed spin torque nano-oscillator consists of a fixed layer and a free rotating layer with an additional anti-ferromagnetic layer, which leads to an exchange bias in the free rotating layer. The spin dynamics of the exchange-biased free rotating layer can be described as an additional exchange field because the exchange bias manifests itself by the existance of a finite exchange bias field. The exchange bias field plays a similar role to that of a finite external field. Hence, microwave generation can be achieved without an external field in the proposed structure.

Electromagnetic Resonant Tunneling System: Double-Magnetic Barriers

  • Kim, Nammee
    • Applied Science and Convergence Technology
    • /
    • v.23 no.3
    • /
    • pp.128-133
    • /
    • 2014
  • We study the ballistic spin transport properties in a two-dimensional electron gas system in the presence of magnetic barriers using a transfer matrix method. We concentrate on the size-effect of the magnetic barriers parallel to a two-dimensional electron gas plane. We calculate the transmission probability of the ballistic spin transport in the magnetic barrier structure while varying the width of the magnetic barriers. It is shown that resonant tunneling oscillation is affected by the width and height of the magnetic barriers sensitively as well as by the inter-spacing of the barriers. We also consider the effect of additional electrostatic modulation on the top of the magnetic barriers, which could enhance the current spin polarization. Because all-semiconductor-based devices are free from the resistance mismatch problem, a resonant tunneling structure using the two-dimensional electron gas system with electric-magnetic modulation would play an important role in future spintronics applications. From the results here, we provide information on the physical parameters of a device to produce well-defined spin-polarized current.

A Study on the Factors Influencing Research-based Spin-Off from the Perspective of Institutional Theory (제도론 관점에서 공공기술기반 창업에 영향을 미치는 요인에 관한 연구)

  • In Jong Lim;Jeong Hwan Lee;Ho Sung Son
    • Journal of the Korean Society of Systems Engineering
    • /
    • v.19 no.1
    • /
    • pp.14-28
    • /
    • 2023
  • The spin-off where the principal technology developers take the lead in the active and initiative pursuit of the commercialization of technologies is increasingly drawing attention, breaking away from the traditional means through the technology transfer or licensing of the public technologies created by the developers. This study aimed to determine the reasons for such differences from the perspective of the institutional theory. The results show that only the start-up support system, profit distribution system for researchers, degree of participation in the technology marketing, entrepreneurship of researchers, the use of start-up systems affected the number of start-ups of spin-off companies. Furthermore, an analysis of success factors and a study on the exploration of success paths for the RSOs will also be required

The Fabrication and Magnetoresistance of Nanometer-sized Spin Device Driven by Current Perpendicular to the Plane (수직전류 인가형 나노 스핀소자의 제조 및 자기저항 특성)

  • Chun, M.G.;Lee, H.J.;Jeung, W.Y.;Kim, K.Y.;Kim, C.G.
    • Journal of the Korean Magnetics Society
    • /
    • v.15 no.2
    • /
    • pp.61-66
    • /
    • 2005
  • In order to make submicron cell for spin-injection device, lift-off method using Pt stencil and wet etching was chosen. This approach allows batch fabrication of stencil substrate with electron-beam lithography. It simplifies the process between magnetic film stack deposition and final device testing, thus enabling rapid turnaround in sample fabrication. Submicron junctions with size of $200nm{\times}300nm$ and $500nm{\times}500nm$ 500 nm and pseudo spin valve structure of $CoFe(30{\AA})/Cu(100{\AA})/CoFe(120{\AA}$) was deposited into the nanojunctions. MR ratio was 0.8 and $1.1{\%}$, respectively and spin transfer effect was confirmed with critical current of $7.65{\times}10^7A/cm^2$.

Configurtion of electron transfer cofactors in photosystem II studied by pulsed EPR

  • Asako Kawamori;NobuhiroKatsuta;Sachiko Arao;Hideyuki Hara;Hiroyuki Mino;Asako Ishii;Ono, Taka-aki;Jun Minagawa
    • Journal of Photoscience
    • /
    • v.9 no.2
    • /
    • pp.379-381
    • /
    • 2002
  • The major electron transfer cofactors in photosystem II have been studied by pulsed EPR, pulsed electron electron double resonance (PELDOR) and laser excited spin polarized electron spin echo envelope modulation (ESEEM) methods, in non-oriented and oriented photosystem II membranes. Distances between radical pairs were determined trom the observed dipole interaction constants to be 27.3 A for P680-QA, 30 A, etc. with the error within 1 A. Angles between the distance vector and membrane normal was determined by orientation dependence of oriented membranes with the accuracy of 5˚ The results were compared with the recent structural data by X-ray analysis.

  • PDF