Spintronics—A retrospective and perspective

Wolf, Stu; Chtchelkanova, Almadena; Treger, Daryl

doi:10.1147/rd.501.0101

Cited by 252 publications

(138 citation statements)

References 56 publications

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“…The normalized value corresponds to the ratio of the contact resistance and the spin resistance of the channel R relaxing, versus those being reabsorbed by the contact, making it a good measure for the influence of the contacts. Equation (1) shows that the spin signal R nl has a maximum for high contact resistances (R → ∞) and is reduced for low R values. A significant change is observed for R/λ 1 [ Fig.…”

Section: Contact-induced Spin Relaxationmentioning

confidence: 99%

Contact-induced spin relaxation in Hanle spin precession measurements

et al. 2012

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Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. In the field of spintronics the "conductivity mismatch" problem remains an important issue. Here the difference between the resistance of ferromagnetic electrodes and a (high resistive) transport channel causes injected spins to be backscattered into the leads and to lose their spin information. We study the effect of the resulting contact-induced spin relaxation on spin transport, in particular on nonlocal Hanle precession measurements. As the Hanle line shape is modified by the contact-induced effects, the fits to Hanle curves can result in incorrectly determined spin transport properties of the transport channel. We quantify this effect that mimics a decrease of the spin relaxation time of the channel reaching more than four orders of magnitude and a minor increase of the diffusion coefficient by less than a factor of two. Then we compare the results to spin transport measurements on graphene from the literature. We further point out guidelines for a Hanle precession fitting procedure that allows the reliable extraction of spin transport properties from measurements.

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Section: Contact-induced Spin Relaxationmentioning

confidence: 99%

Contact-induced spin relaxation in Hanle spin precession measurements

et al. 2012

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“…The semiconductors showing ferromagnetic ordering at room temperature turned on large interest in the last several years due to the possibility to utilize them in the future spintronic devices [1]. The most intensively studied diluted magnetic semiconductor (DMS) was Ga 1−x Mn x As with the Curie temperatures much lower than T = 300 K (maximum T C ≈ 173 K [2]).…”

Section: Introductionmentioning

confidence: 99%

Zn_1-x(Mn,Co)_xGeAs₂Ferromagnetic Semiconductor: Magnetic and Transport Properties

et al. 2008

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We present the studies of magnetic and transport properties of the bulk Zn 1−x (Mn,Co) x GeAs 2 mixed crystals with 0.052 ≤ x ≤ 0.182 grown using direct fusion method. Magnetic investigations showed that for samples with x ≥ 0.078 we observed a behavior typical of ferromagnets, with the Curie temperatures TC ≥ 300 K. The observed ferromagnetism was probably connected with the spinodal decomposition of the Mn ions in the alloy. The transport studies including resistivity and Hall effect (at B = 1.4 T) were performed. The samples showed p-type conductivity with semiconducting or metallic character, depending on the alloy composition. The Hall carrier concentration, p ≥ 10 18 cm −3 , was composition dependent.

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“…The interest from the physics perspective stems from the need to advance the understanding of magnetization dynamics in nonlinear systems [1][2][3][4][5] . From the applications perspective, these devices find suitability in the modern communication electronics [6][7][8] . STNOs have better in-built features over traditionally used voltage control oscillators (VCOs), such as smaller size, lower cost and easier integrability to silicon technology.…”

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confidence: 99%

Resonant Spin-Transfer-Torque Nano-Oscillators

2017

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Spin transfer torque nano-oscillators are potential candidates for replacing the traditional inductor based voltage controlled oscillators in modern communication devices. Typical oscillator designs are based on trilayer magnetic tunnel junctions which are disadvantaged by low power outputs and poor conversion efficiencies. In this letter, we theoretically propose to use resonant spin filtering in pentalayer magnetic tunnel junctions as a possible route to alleviate these issues and present device designs geared toward a high microwave output power and an efficient conversion of the d.c. input power. We attribute these robust qualities to the resulting non-trivial spin current profiles and the ultra high tunnel magnetoresistance, both arising from resonant spin filtering. The device designs are based on the nonequilibrium Green's function spin transport formalism self-consistently coupled with the stochastic Landau-Lifshitz-Gilbert-Slonczewski's equation and the Poisson's equation. We demonstrate that the proposed structures facilitate oscillator designs featuring a large enhancement in microwave power of around 775% and an efficiency enhancement of over 1300% in comparison with typical trilayer designs. We also rationalize the optimum operating regions via an analysis of the dynamic and static device resistances. This work sets stage for pentalyer spin transfer torque nano-oscillator device designs that extenuate most of the issues faced by the typical trilayer designs.Spin transfer torque nano-oscillators (STNOs) are a class of non-linear nanoscale oscillators which have attracted a lot of interest from the physics as well as the applications perspective. The interest from the physics perspective stems from the need to advance the understanding of magnetization dynamics in nonlinear systems [1][2][3][4][5] . From the applications perspective, these devices find suitability in the modern communication electronics 6-8 . STNOs have better in-built features over traditionally used voltage control oscillators (VCOs), such as smaller size, lower cost and easier integrability to silicon technology. In order to technologically replace VCOs, STNOs should be able to deliver high microwave power outputs and must possess higher conversion efficiencies with a good quality factor. There have been consistent efforts 9-11 to improve the performance of STNOs based on typical trilayer magnetic tunnel junctions (MTJ). Various improvements proposed are centered around modifying the magnetic properties of the ferromagnet (FM). However, they have not been able to deliver microwave power outputs in excess of 0.3µW 11 . In this work we propose pentalayer device designs that make use of resonant spin filtering, termed as resonant tunneling magnetic tunnel junction (RTMTJ) structures, to circumvent these issues faced by typical trilayer based STNO designs. We demonstrate that owing to the novel spin-filtering physics in the proposed structures 12,13 , the resulting non-trivial spin current profiles and the high tunnel magneto resistanc...

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Spintronics—A retrospective and perspective

Cited by 252 publications

References 56 publications

Contact-induced spin relaxation in Hanle spin precession measurements

Contact-induced spin relaxation in Hanle spin precession measurements

Zn_1-x(Mn,Co)_xGeAs₂Ferromagnetic Semiconductor: Magnetic and Transport Properties

Resonant Spin-Transfer-Torque Nano-Oscillators

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Spintronics—A retrospective and perspective

Cited by 252 publications

References 56 publications

Contact-induced spin relaxation in Hanle spin precession measurements

Contact-induced spin relaxation in Hanle spin precession measurements

Zn1-x(Mn,Co)xGeAs2Ferromagnetic Semiconductor: Magnetic and Transport Properties

Resonant Spin-Transfer-Torque Nano-Oscillators

Contact Info

Product

Resources

About

Zn_1-x(Mn,Co)_xGeAs₂Ferromagnetic Semiconductor: Magnetic and Transport Properties