scholarly journals Nonmagnetic single-molecule spin-filter based on quantum interference

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Atindra Nath Pal ◽  
Dongzhe Li ◽  
Soumyajit Sarkar ◽  
Sudipto Chakrabarti ◽  
Ayelet Vilan ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Single Molecule ◽  
Quantum Interference ◽  
Spin Transport ◽  
Spin Current ◽  
Spin Transfer Torque ◽  
Spin Splitting ◽  
Spin Polarized ◽  
Noise Measurements ◽  
Low Sensitivity

AbstractKey spin transport phenomena, including magnetoresistance and spin transfer torque, cannot be activated without spin-polarized currents, in which one electron spin is dominant. At the nanoscale, the relevant length-scale for modern spintronics, spin current generation is rather limited due to unwanted contributions from poorly spin-polarized frontier states in ferromagnetic electrodes, or too short length-scales for efficient spin splitting by spin-orbit interaction and magnetic fields. Here, we show that spin-polarized currents can be generated in silver-vanadocene-silver single molecule junctions without magnetic components or magnetic fields. In some cases, the measured spin currents approach the limit of ideal ballistic spin transport. Comparison between conductance and shot-noise measurements to detailed calculations reveals a mechanism based on spin-dependent quantum interference that yields very efficient spin filtering. Our findings pave the way for nanoscale spintronics based on quantum interference, with the advantages of low sensitivity to decoherence effects and the freedom to use non-magnetic materials.

Magnetotransport Properties in a Lateral Spin-Injection Device with a Ferromagnetic/Si/ Ferromagnetic Junction

2004 ◽  
Vol 449-452 ◽  
pp. 1081-1084
Author(s):  
Woong Joon Hwang ◽  
H.J. Lee ◽  
K.I. Lee ◽  
J.M. Lee ◽  
J.Y. Chang ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Spin Transport ◽  
Spin Injection ◽  
The Other ◽  
Injection Device ◽  
Polarized Electrons ◽  
Spin Polarized ◽  
First Contact

The spin transport in a lateral spin-injection device with an FeCo/Si/FeCo junction has been investigated. Magnetoresistance (MR) signals were found to appear at low magnetic fields in the range 4 – 300 K. This is attributable to the switching of the magnetization of the two ferromagnetic contacts in the device for certain magnetic fields over which the magnetization in one contact is aligned antiparallel to that in the other. Our results suggest that the spin-polarized electrons are injected from the first contact and, after propagating through the bulk Si, are collected by the second contact.

Spin polarization in magnets

2017 ◽  
Author(s):  
K. Takanashi ◽  
Y. Sakuraba
Keyword(s):  
Spin Polarization ◽  
Spin Current ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Energy Band Gap ◽  
Magnetoresistance Effect ◽  
Half Metals ◽  
Conduction Electrons ◽  
Spin Polarized ◽  
Spin Dependent Scattering

This chapter explains how the exchange splitting between up- and down-spin bands in ferromagnets unexceptionally generates spin-polarized electronic states at the Fermi energy. The quantity of spin polarization P in ferromagnets is one of the important parameters for application in spintronics, since a ferromagnet having a higher P is able to generate larger various spin-dependent effects such as the magnetoresistance effect, spin transfer torque, spin accumulation, and so on. However, the spin polarizations of general 3d transition metals or alloys generally limit the size of spin-dependent effects. Thus,“‘half-metals” attract much interest as an ideal source of spin current and spin-dependent scattering because they possess perfectly spin-polarized conduction electrons due to the energy band gap in either the up- or down-spin channel at the Fermi level.

TUNNELING BETWEEN SPIN POLARIZED EDGE STATES STUDIED AT HIGH MAGNETIC FIELDS

2004 ◽  
Vol 18 (27n29) ◽  
pp. 3649-3652 ◽  
Author(s):  
G. SUKHODUB ◽  
F. HOHLS ◽  
R. J. HAUG ◽  
D. K. MAUDE ◽  
D. REUTER ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Electron System ◽  
Spin Splitting ◽  
Edge States ◽  
Dimensional Electron ◽  
Energy Gaps ◽  
Lowest Landau Level ◽  
Wide Range ◽  
Spin Polarized ◽  
Dimensional Electron System

We utilize the tunneling between edge states of the lowest Landau level to study the behavior of the spin splitting in a wide range of magnetic fields up to 28 T. We find that the Zeeman energy with the bare |g*|=0.44 of GaAs mainly accounts for the observed threshold in the bias voltage between edge states. There is no evidence for the exchange interaction considerably affecting the measured energy gaps at the edge of a two-dimensional electron system.

scholarly journals Controllable Spin Switching in a Single-Molecule Magnetic Tunneling Junction

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Zhengzhong Zhang ◽  
Ya Wang ◽  
Haiou Wang ◽  
Hao Liu ◽  
Liming Dong
Keyword(s):  
Single Molecule ◽  
Spin Current ◽  
Tunneling Junction ◽  
Metal Electrodes ◽  
Molecular Orbit ◽  
Spin Polarized ◽  
New Type ◽  
Magnetic Tunneling ◽  
Spin Switching ◽  
Ground State Doublet

AbstractA new type of spin-current filter is proposed that consists of a single-molecule magnet (SMM) coupled to two normal metal electrodes. It is shown that this tunneling junction can generate a highly spin-polarized current, whose spin polarization can be switched by means of magnetic fields and gate voltages applied to the SMM. This spin switching in the SMM tunnel junction arises from spin-selective single-electron resonant tunneling via the lowest unoccupied molecular orbit of the SMM. The electron current spectrum is still spin polarized in the absence of an external magnetic field, which can help to judge whether the molecule’s spin state has reached the ground-state doublet $$|\pm S\rangle$$ | ± S ⟩ . This device can be realized with current technologies and may have practical use in spintronics and quantum information.

scholarly journals Controllable spin switching in a single-molecule magnetic tunneling junction

2020 ◽  
Author(s):  
Zhengzhong Zhang ◽  
Ya Wang ◽  
Haiou Wang ◽  
Hao Liu ◽  
Liming Dong
Keyword(s):  
Single Molecule ◽  
Spin Current ◽  
Tunneling Junction ◽  
Metal Electrodes ◽  
Molecular Orbit ◽  
Spin Polarized ◽  
New Type ◽  
Magnetic Tunneling ◽  
Spin Switching ◽  
Ground State Doublet

Abstract A new type of spin-current filter is proposed that consists of a single molecule magnet (SMM) coupled to two normal metal electrodes. It is shown that this tunneling junction can generate a highly spin-polarized current, whose spin polarization can be switched by means of magnetic fields and gate voltages applied to the SMM. This spin switching in the SMM tunnel junction arises from spin-selective single electron resonant tunneling via the lowest unoccupied molecular orbit of the SMM. The electron current spectrum is still spin polarized in the absence of an external magnetic field, which can help to judge whether the molecule’s spin state has reached the ground-state doublet |± S > . This device can be realized with current technologies and may have practical use in spintronics and quantum information.

scholarly journals Controllable spin switch in a single-molecule magnet tunneling junction

2020 ◽  
Author(s):  
Zhengzhong Zhang ◽  
Hao Liu
Keyword(s):  
Magnetic Field ◽  
Single Molecule ◽  
Spin Current ◽  
Tunneling Junction ◽  
Metal Electrodes ◽  
Single Molecule Magnet ◽  
Molecular Orbit ◽  
Spin Polarized ◽  
New Type ◽  
Spin Switch

Abstract A new type of spin-current filter is proposed, which consists of a single-molecule magnet (SMM) coupled to two normal metal electrodes. It is shown that this tunneling junction can generate a highly spin-polarized current, whose spin polarization can be switched by the magnetic field and gate voltage applied to the SMM. Such a spin switching in the SMM tunnel junction arises from the spin-selected single electron resonant tunneling via the lowest unoccupied molecular orbit of the SMM. And the electron current spectrum in absences of external magnetic field is still spin-polarized, which can help us to judge if the molecule’s spin state has reach to the ground-state doublet |±S). This device can be realized with current technologies and may have practical use in spintronics and quantum information.PACS numbers: 72.25.-b, 75.50.Xx, 85.75.-d

Mechanically-Tunable Quantum Interference in Ferrocene-Based Single-Molecule Junctions

2020 ◽  
Author(s):  
María Camarasa-Gómez ◽  
Daniel Hernangómez-Pérez ◽  
Michael S. Inkpen ◽  
Giacomo Lovat ◽  
E-Dean Fung ◽  
...  
Keyword(s):  
Single Molecule ◽  
Quantum Interference ◽  
Degrees Of Freedom ◽  
Building Blocks ◽  
Ferrocene Derivative ◽  
Single Molecule Junctions ◽  
Molecule Junction ◽  
Single Molecule Junction ◽  
The Impact ◽  
D Orbitals

Ferrocenes are ubiquitous organometallic building blocks that comprise a Fe atom sandwiched between two cyclopentadienyl (Cp) rings that rotate freely at room temperature. Of widespread interest in fundamental studies and real-world applications, they have also attracted<br>some interest as functional elements of molecular-scale devices. Here we investigate the impact of<br>the configurational degrees of freedom of a ferrocene derivative on its single-molecule junction<br>conductance. Measurements indicate that the conductance of the ferrocene derivative, which is<br>suppressed by two orders of magnitude as compared to a fully conjugated analog, can be modulated<br>by altering the junction configuration. Ab initio transport calculations show that the low conductance is a consequence of destructive quantum interference effects that arise from the hybridization of metal-based d-orbitals and the ligand-based π-system. By rotating the Cp rings, the hybridization, and thus the quantum interference, can be mechanically controlled, resulting in a conductance modulation that is seen experimentally.<br>

Charge Transfer Complexation Boosts Molecular Conductance Through Fermi Level Pinning

2018 ◽  
Author(s):  
Kun Wang ◽  
Andrea Vezzoli ◽  
Iain Grace ◽  
Maeve McLaughlin ◽  
Richard Nichols ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Single Molecule ◽  
Quantum Interference ◽  
Transmission Function ◽  
Scanning Tunneling ◽  
Charge Transfer Complexes ◽  
Tunneling Microscopy ◽  
Quantum Interference Effect ◽  
Single Molecule Junctions ◽  
Charge Transfer Complexation

We have used scanning tunneling microscopy to create and study single molecule junctions with thioether-terminated oligothiophene molecules. We find that the conductance of these junctions increases upon formation of charge transfer complexes of the molecules with tetracyanoethene, and that the extent of the conductance increase is greater the longer is the oligothiophene, i.e. the lower is the conductance of the uncomplexed molecule in the junction. We use non-equilibrium Green's function transport calculations to explore the reasons for this theoretically, and find that new resonances appear in the transmission function, pinned close to the Fermi energy of the contacts, as a consequence of the charge transfer interaction. This is an example of a room temperature quantum interference effect, which in this case boosts junction conductance in contrast to earlier observations of QI that result in diminished conductance.<br>

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