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Quantum-well resonance is achieved through partial confinement in magnetic tunnel junctions (MTJs), which provides an additional operable degree of freedom to regulate quantum-well levels. Using Al/Fe/MgO/Fe/Al and Ag/Al/Fe/MgO/Fe/Al/Ag…

Materials Science · Physics 2024-04-09 L. N. Jiang , B. Y. Chi , W. Z. Chen , X. F. Han

Spin-diodes are usually resonant in nature (GHz frequency) and tuneable by magnetic field and bias current with performances, in terms of sensitivity and minimum detectable power, overcoming the semiconductor counterpart, i.e. Schottky…

We have measured the bias voltage and field dependence of eigenmode frequencies in a magnetic tunnel junction with MgO barrier. We show that both free layer (FL) and reference layer (RL) modes are excited, and that a cross-over between…

Materials Science · Physics 2016-08-14 P. K. Muduli , O. G. Heinonen , Johan Åkerman

We compute thermal spin transfer torques (TST) in Fe-MgO-Fe tunnel junctions using a first principles wave function-matching method. At room temperature, the TST in a junction with 3 MgO monolayers amounts to 10^-7J/m^2/K, which is…

Materials Science · Physics 2011-10-24 Xingtao Jia , Ke Xia , Gerrit E. W. Bauer

The spin-transfer effect has been studied in magnetic tunnel junctions (PtMn/CoFe/Ru/CoFe/Al2O3/CoFe/NiFe) with dimensions down to 0.1x0.2 um2 and resistance-area product RA in the range of 0.5-10 Ohm m2 (dR/R=1-20%). Current-induced…

Other Condensed Matter · Physics 2009-11-11 Yiming Huai , Frank Albert , Paul Nguyen , Mahendra Pakala , Thierry Valet

Replacing the ferromagnet with ferrimagnet (FiM) in the magnetic tunnel junction (MTJ) allows faster magnetization switching in picoseconds. The operation of a memory cell that consists of the MTJ and a transistor requires reversable…

Mesoscale and Nanoscale Physics · Physics 2024-11-12 Zhuo Xu , Zhengping Yuan , Xue Zhang , Zhengde Xu , Yixiao Qiao , Yumeng Yang , Zhifeng Zhu

We report on room temperature magnetoresistance and low frequency noise in sub-100nm elliptic CoFeB/MgO/CoFeB magnetic tunnel junctions with ultrathin (0.9nm) barriers. For magnetic fields applied along the hard axis, we observe current…

Mesoscale and Nanoscale Physics · Physics 2013-05-28 J. P. Cascales , D. Herranz , J. L. Sambricio , U. Ebels , J. A. Katine , F. G. Aliev

We propose a theoretical model of magnetization switching in a ferromagnetic multilayer by both electric current and microwaves. The electric current gives a spin transfer torque on the magnetization, while the microwaves induce a…

Mesoscale and Nanoscale Physics · Physics 2016-01-22 Tomohiro Taniguchi , Daisuke Saida , Yoshinobu Nakatani , Hitoshi Kubota

We report the observation and micromagnetic analysis of current-driven magnetization switching in nanoscale ring-shaped magnetic tunnel junctions. When the electric current density exceeds a critical value of the order of $6\times…

Materials Science · Physics 2009-11-13 Hong-Xiang Wei , Jiexuan He , Zhen-Chao Wen , Xiu-Feng Han , Wen-Shan Zhan , Shufeng Zhang

In the absence of any external applied magnetic field, we have found that a magnetic tunnel junction (MTJ) can produce a significant output direct voltage under microwave radiation at frequencies, which are far from the ferromagnetic…

Mesoscale and Nanoscale Physics · Physics 2015-06-24 Y. S. Gui , Y. Xiao , L. H. Bai , S. Hemour , Y. P. Zhao , D. Houssameddine , K. Wu , H. Guo , C. -M. Hu

We explore the prospects of wafer scale inductive probing of the critical current density $j^{c0}$ for spin transfer torque switching of a CoFeB/MgO/CoFeB magnetic tunnel junction with varying MgO thickness. From inductive measurements…

Control of magnetism without using magnetic fields enables large-scale integration of spintronic devices for memory, computation and communication in the beyond-CMOS era. Mechanisms including spin torque transfer, spin Hall effect, and…

Materials Science · Physics 2017-03-08 Jun-Yang Chen , Li He , Jian-Ping Wang , Mo Li

We fabricated fully epitaxial Fe/ZnO/MgO/Fe magnetic tunnel junctions (MTJs) with low junction resistance-area products (several $\Omega$ $\mu$m$^2$) and conducted a theoretical estimation of square-low rectifying performance for a…

Applied Physics · Physics 2020-01-17 Hidekazhi Saito , Hiroshi Imamura

Magnetic tunnel junctions (MTJs) are elementary units of magnetic memory devices. For high-speed and low-power data storage and processing applications, fast reversal by an ultrashort laser pulse is extremely important. We demonstrate…

The spin-transfer nano-oscillator (STNO) offers the possibility of using the transfer of spin angular momentum via spin-polarized currents to generate microwave signals. However, at present STNO microwave emission mainly relies on both…

A magnetic vortex core in a ferromagnetic circular nanodot has a resonance frequency originating from the confinement of the vortex core. By the micromagnetic simulation including the spin-transfer torque, we show that the vortex core can…

Other Condensed Matter · Physics 2009-11-11 Shinya Kasai , Yoshinobu Nakatani , Kensuke Kobayashi , Hiroshi Kohno , Teruo Ono

The Modulated Wideband Converter (MWC) is a recently proposed analog-to-digital converter (ADC) based on Compressive Sensing (CS) theory. Unlike conventional ADCs, its quantization reference voltage, which is important to the system…

Information Theory · Computer Science 2012-03-09 Yaming Wang , Laming Chen , Yuantao Gu

We present an experimental study of the power spectrum of current-driven magnetization oscillations in MgO tunnel junctions under low bias. We find the existence of narrow spectral lines, down to 8 MHz in width at a frequency of 10.7 GHz,…

The effects of a weak microwave field in the magnetization dynamics driven by spin-transfer-torque in spin-valves with perpendicular materials have been systematically studied by means of full micromagnetic simulations. In the system we…

Mesoscale and Nanoscale Physics · Physics 2015-05-19 Mario Carpentieri , Giovanni Finocchio , Bruno Azzerboni , Luis Torres

We report measurements of magnetic switching and steady-state magnetic precession driven by spin-polarized currents in nanoscale magnetic tunnel junctions with low-resistance, < 5 Ohm-micron-squared, barriers. The current densities required…