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SPIN HALL OSCILLATOR, MAGNETIC RECORDING DEVICE, AND CALCULATOR

Foreign code F200010232
File No. (S2019-0186-N0)
Posted date 2020年10月29日
Country 世界知的所有権機関(WIPO)
International application number 2020JP007010
International publication number WO2020179493
Date of international filing 令和2年2月21日(2020.2.21)
Date of international publication 令和2年9月10日(2020.9.10)
Priority data
  • 特願2019-037682 (2019.3.1) JP
Title SPIN HALL OSCILLATOR, MAGNETIC RECORDING DEVICE, AND CALCULATOR
Abstract This oscillator 100A comprises a spin current source 110 and a free layer 111 that is joined to the spin current source 100. The free layer 111 has a magnetization-hard axis parallel to a quantization axis of a spin current injected by the spin hall effect of the spin current source 110.
Outline of related art and contending technology BACKGROUND ART
In recent years, a microwave oscillator utilizing spin torque has attracted attention because of its high Q value, high controllability of oscillation frequency by current, easy integration by CMOS technology, and so on. A microwave oscillator utilizing spin torque is called a spin torque oscillator (STO). STO utilizes precession of magnetization generated when a spin current is injected into the magnetic body.
The method of extracting microwaves from the precession of magnetization is roughly classified into 2 types. The 1 th method is a method of directly utilizing a high-frequency leakage magnetic field generated by precession magnetization. In the 2 th method, the precession of magnetization is extracted as an electric signal by utilizing the tunneling magneto-resistance (TMR) effect, converted into microwaves, and emitted. The 1 th method is simple in principle, but has a drawback that microwaves can be irradiated only at a short distance. On the other hand, the 2 th method must constitute a magnetic tunnel junction (MTJ) structure. However, since the microwave output per 1 devices is stronger than that of a method for extracting a leakage magnetic field, attention has been paid to.
STO is classified into 2 types according to the spin current generation method. The 1 th method utilizes spin polarization, and a spin current parallel to a charge current is generated by passing the charge current through the fixed layer of MTJ. At this time, the generation efficiency of the spin current is determined by the spin polarization rate of the fixed layer. Since the spin polarization rate does not exceed 1 in principle, the spin current generation efficiency is low, and a large current is required for oscillation. As an example, in Non-Patent Document 1, 110μA is required for oscillation at 0.9GHz. However, the structure of the free layer was standardized to have a length 50 nm, a width 50 nm, and a thickness 2 nm. When spin polarization is used, this large current passes through MTJ, which lowers the durability of MTJ and brings about a problem in the reliability of the oscillator.
The 2 th method utilizes the spin Hall effect, and a spin current perpendicular to the charge current is generated by passing the charge current through a spin current source composed of a material having strong spin orbit interaction. Therefore, a spin current source is joined to the magnetic layer which performs precession, and a charge current is applied to the spin current source in parallel with the joining surface. At this time, the generation efficiency of the spin current is determined by the spin hole angle of the spin current source and the ratio of the length and film thickness of the spin current source, and both parameters may exceed 1. Therefore, the spin current can be efficiently generated by the method utilizing the spin Hall effect. Further, since the spin Hall effect generates a spin current perpendicular to the charge current, the charge current for generating the spin current does not pass through MTJ. Thus, it is expected that the reliability of the oscillator can be improved.
  • Applicant
  • ※All designated countries except for US in the data before July 2012
  • TOKYO INSTITUTE OF TECHNOLOGY
  • Inventor
  • PHAM Nam Hai
  • SHIROKURA Takanori
IPC(International Patent Classification)
Specified countries National States: AE AG AL AM AO AT AU AZ BA BB BG BH BN BR BW BY BZ CA CH CL CN CO CR CU CZ DE DJ DK DM DO DZ EC EE EG ES FI GB GD GE GH GM GT HN HR HU ID IL IN IR IS JO JP KE KG KH KN KP KR KW KZ LA LC LK LR LS LU LY MA MD ME MG MK MN MW MX MY MZ NA NG NI NO NZ OM PA PE PG PH PL PT QA RO RS RU RW SA SC SD SE SG SK SL ST SV SY TH TJ TM TN TR TT TZ UA UG US UZ VC VN WS ZA ZM ZW
ARIPO: BW GH GM KE LR LS MW MZ NA RW SD SL SZ TZ UG ZM ZW
EAPO: AM AZ BY KG KZ RU TJ TM
EPO: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR
OAPI: BF BJ CF CG CI CM GA GN GQ GW KM ML MR NE SN ST TD TG
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