scholarly journals Spin-neutral currents for spintronics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ding-Fu Shao ◽  
Shu-Hui Zhang ◽  
Ming Li ◽  
Chang-Beom Eom ◽  
Evgeny Y. Tsymbal
Keyword(s):  
Fermi Surface ◽  
Spin Polarization ◽  
Tunnel Junctions ◽  
Relative Orientation ◽  
Group Symmetry ◽  
Tunneling Magnetoresistance ◽  
Neutral Currents ◽  
Spintronic Devices ◽  
Normal Metals ◽  
Antiferromagnetic Layer

AbstractElectric currents carrying a net spin polarization are widely used in spintronics, whereas globally spin-neutral currents are expected to play no role in spin-dependent phenomena. Here we show that, in contrast to this common expectation, spin-independent conductance in compensated antiferromagnets and normal metals can be efficiently exploited in spintronics, provided their magnetic space group symmetry supports a non-spin-degenerate Fermi surface. Due to their momentum-dependent spin polarization, such antiferromagnets can be used as active elements in antiferromagnetic tunnel junctions (AFMTJs) and produce a giant tunneling magnetoresistance (TMR) effect. Using RuO2 as a representative compensated antiferromagnet exhibiting spin-independent conductance along the [001] direction but a non-spin-degenerate Fermi surface, we design a RuO2/TiO2/RuO2 (001) AFMTJ, where a globally spin-neutral charge current is controlled by the relative orientation of the Néel vectors of the two RuO2 electrodes, resulting in the TMR effect as large as ~500%. These results are expanded to normal metals which can be used as a counter electrode in AFMTJs with a single antiferromagnetic layer or other elements in spintronic devices. Our work uncovers an unexplored potential of the materials with no global spin polarization for utilizing them in spintronics.

scholarly journals THE IMPORTANCE OF Fe SURFACE STATES FOR MAGNETIC TUNNEL JUNCTION BASED SPINTRONIC DEVICES

2008 ◽  
Vol 22 (26) ◽  
pp. 2529-2551 ◽  
Author(s):  
ATHANASIOS N. CHANTIS ◽  
KIRILL D. BELASHCHENKO ◽  
EVGENY Y. TSYMBAL ◽  
INNA V. SUS
Keyword(s):  
Spin Polarization ◽  
Tunnel Junctions ◽  
Strong Dependence ◽  
Magnetic Tunnel Junctions ◽  
Interface States ◽  
Tunneling Magnetoresistance ◽  
Sign Reversal ◽  
Spintronic Devices ◽  
Spin Electronics ◽  
Minority Spin

In this article we give a review of our recent theoretical studies of the influence of Fe (001) surface (interface) states on spin-polarized electron transport across magnetic tunnel junctions with Fe electrodes. We show that minority-spin surface (interface) states are responsible for at least two effects which are important for spin electronics. First, they can produce a sizable tunneling anisotropic magnetoresistance in magnetic tunnel junctions with a single Fe electrode. The effect is driven by a Rashba shift of the resonant surface band when the magnetization changes direction. This can introduce a new class of spintronic devices, namely, tunneling magnetoresistance junctions with a single ferromagnetic electrode. Second, in Fe/GaAs (001) magnetic tunnel junctions minority-spin interface states produce a strong dependence of the tunneling current spin polarization on applied electrical bias. A dramatic sign reversal within a voltage range of just a few tenths of an eV is predicted. This explains the observed sign reversal of spin polarization in recent experiments of electrical spin injection in Fe/GaAs (001) and related reversal of tunneling magnetoresistance through vertical Fe/GaAs/Fe trilayers.

Spin-filtering and tunneling magnetoresistance effects in 6,6,12-graphyne-based molecular magnetic tunnel junctions

2019 ◽  
Vol 21 (5) ◽  
pp. 2734-2742 ◽  
Author(s):  
Jin Li ◽  
Maoyun Di ◽  
Zhi Yang ◽  
Li-Chun Xu ◽  
Yongzhen Yang ◽  
...  
Keyword(s):  
Tunnel Junctions ◽  
Graphene Nanoribbons ◽  
Magnetic Tunnel Junctions ◽  
Tunneling Magnetoresistance ◽  
Spintronic Devices ◽  
Zigzag Graphene Nanoribbons ◽  
Spin Filtering

By designing two kinds of molecular magnetic tunnel junctions based on 6,6,12-graphyne and zigzag graphene nanoribbons, the spin-filtering and tunneling magnetoresistance effects of spintronic devices can be dramatically enhanced.

scholarly journals Negative Spin Polarization and Large Tunneling Magnetoresistance in EpitaxialCo|SrTiO3|CoMagnetic Tunnel Junctions

2005 ◽  
Vol 95 (21) ◽  
Author(s):  
J. P. Velev ◽  
K. D. Belashchenko ◽  
D. A. Stewart ◽  
M. van Schilfgaarde ◽  
S. S. Jaswal ◽  
...  
Keyword(s):  
Spin Polarization ◽  
Tunnel Junctions ◽  
Tunneling Magnetoresistance

scholarly journals Reducing Dzyaloshinskii-Moriya interaction and field-free spin-orbit torque switching in synthetic antiferromagnets

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ruyi Chen ◽  
Qirui Cui ◽  
Liyang Liao ◽  
Yingmei Zhu ◽  
Ruiqi Zhang ◽  
...  
Keyword(s):  
Domain Wall ◽  
Tunnel Junctions ◽  
Low Power Consumption ◽  
Stray Field ◽  
Magnetic Memory ◽  
Spin Orbit ◽  
Theoretic Analysis ◽  
Spintronic Devices ◽  
Deterministic Switching ◽  
Moriya Interaction

AbstractPerpendicularly magnetized synthetic antiferromagnets (SAF), possessing low net magnetization and high thermal stability as well as easy reading and writing characteristics, have been intensively explored to replace the ferromagnetic free layers of magnetic tunnel junctions as the kernel of spintronic devices. So far, utilizing spin-orbit torque (SOT) to realize deterministic switching of perpendicular SAF have been reported while a large external magnetic field is typically needed to break the symmetry, making it impractical for applications. Here, combining theoretic analysis and experimental results, we report that the effective modulation of Dzyaloshinskii-Moriya interaction by the interfacial crystallinity between ferromagnets and adjacent heavy metals plays an important role in domain wall configurations. By adjusting the domain wall configuration between Bloch type and Néel type, we successfully demonstrate the field-free SOT-induced magnetization switching in [Co/Pd]/Ru/[Co/Pd] SAF devices constructed with a simple wedged structure. Our work provides a practical route for utilization of perpendicularly SAF in SOT devices and paves the way for magnetic memory devices with high density, low stray field, and low power consumption.

scholarly journals Surface acoustic wave induced modulation of tunneling magnetoresistance in magnetic tunnel junctions

2021 ◽  
Vol 130 (3) ◽  
pp. 033901
Author(s):  
Dhritiman Bhattacharya ◽  
Peng Sheng ◽  
Md Ahsanul Abeed ◽  
Zhengyang Zhao ◽  
Hongshi Li ◽  
...  
Keyword(s):  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Tunnel Junctions ◽  
Magnetic Tunnel Junctions ◽  
Tunneling Magnetoresistance ◽  
Wave Induced

MAGNETORESISTANCE IN Fe/MgO/Fe MAGNETIC TUNNEL JUNCTIONS

2007 ◽  
Vol 17 (03) ◽  
pp. 593-598 ◽  
Author(s):  
N. N. BELETSKII ◽  
S. A. BORYSENKO ◽  
V. M. YAKOVENKO ◽  
G. P. BERMAN ◽  
S. A. WOLF
Keyword(s):  
Current Density ◽  
Tunnel Junctions ◽  
Magnetic Tunnel Junctions ◽  
Tunneling Magnetoresistance ◽  
Electron Current ◽  
Ferromagnetic Electrode ◽  
Electron Current Density

The magnetoresistance of Fe/MgO/Fe magnetic tunnel junctions (MTJs) was studied taking into consideration image forces. For MTJs with an MgO insulator, explanations are given of the giant tunneling magnetoresistance (TMR) effect and the effect of the increasing TMR with an increase in MgO insulator thickness. It is demonstrated that the electron current density through MTJs can be high enough to switch the magnetization of a ferromagnetic electrode.

Investigation of spin polarization in Gd-doped ZnO films for high-performance organic spintronic devices

2022 ◽  
Vol 276 ◽  
pp. 115536
Author(s):  
Norhidayah Che Ani ◽  
Mohd Zainizan Sahdan ◽  
Nafarizal Nayan ◽  
Feri Adriyanto ◽  
Kusnanto Mukti Wibowo
Keyword(s):  
Spin Polarization ◽  
High Performance ◽  
Zno Films ◽  
Spintronic Devices ◽  
Doped Zno

Magnetism and Spin Tunneling in Nanostructures

1997 ◽  
Vol 491 ◽  
Author(s):  
Alexander Bratkovsky
Keyword(s):  
Spin Polarization ◽  
Tunnel Junctions ◽  
Iron Group ◽  
Defect States ◽  
Resistance Change ◽  
Half Metallic ◽  
Spin Tunneling ◽  
Inelastic Tunneling ◽  
Resonant Tunnel ◽  
General Method

ABSTRACTIn the present paper different tunneling mechanisms in conventional and half-metallic ferromagnetic tunnel junctions are analyzed within the same general method. Theoretically calculated direct tunneling in iron group systems leads to about a 30% change in resistance, which is close but lower than experimentally observed values. It is shown that the larger observed values of the TMR might be a result of tunneling involving surface polarized states. We find that tunneling via resonant defect states in the barrier radically decreases the TMR (down to 4% with Fe-based electrodes), and a resonant tunnel diode structure would give a TMR of about 8%. With regards to inelastic tunneling, magnons and phonons exhibit opposite effects: one-magnon emission generally results in spin mixing and, consequently, reduces the TMR, whereas phonons are shown to enhance the TMR. The inclusion of both magnons and phonons reasonably explains an unusual bias dependence of the TMR.The model presented here is applied qualitatively to half-metallics with 100% spin polarization, where one-magnon processes are suppressed and the change in resistance in the absence of spin-mixing on impurities may be arbitrarily large. Even in the case of imperfect magnetic configurations, the resistance change can be a few 1000 percent. Examples of half-metallic systems are CrO2/TiO2 and CrO2/RuO2, and an account of their peculiar band structures is presented. The implications and relation of these systems to CMR materials, which are nearly half-metallic, are discussed.

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