Single Molecule Magnetoresistance with Combined Antiferromagnetic and Ferromagnetic Electrodes

Bagrets, A.; Schmaus, Stefan; Jaafar, Ali; Kramczynski, Detlef; Yamada, Toyo Kazu; Alouani, M.; Wulfhekel, Wulf; Evers, Ferdinand

doi:10.1021/nl301967t

Cited by 47 publications

(47 citation statements)

References 23 publications

(35 reference statements)

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“…At the single molecule scale, more than 100% of MRR were predicted theoretically for Fe/C 60 /Fe magnetic junctions 4 , and moderate values of MRR up to 60% were recently reported 5,6 . These effects were attributed to the spin dependent hybridization occurring at the ferromagnet/molecule interface.…”

Section: Introductionmentioning

confidence: 93%

Symmetry aspects of spin filtering in molecular junctions: Hybridization and quantum interference effects

Banerjee

Mondal

et al. 2019

Phys. Rev. B

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Control and manipulation of electric current and, especially, its degree of spin polarization (spin filtering) across single molecules are currently of great interest in the field of molecular spintronics. We explore one possible strategy based on the modification of nanojunction symmetry which can be realized, for example, by a mechanical strain. Such modification can activate new molecular orbitals which were inactive before due to their orbital mismatch with the electrodes conduction states. This can result in several important consequences such as (i) quantum interference effects appearing as Fano-like features in electron transmission and (ii) the change in molecular level hybridization with the electrodes states. We argue that the symmetry change can affect very differently two majority-and minority-spin conductances and thus alter significantly the resulting spin-filtering ratio as the junction symmetry is modified.We illustrate the idea for two basic molecular junctions: Ni/benzene/Ni (perpendicular vs tilted orientations) and Ni/Si chain/Ni (zigzag vs linear chains). In both cases, one highest occupied molecular orbital (HOMO) and one lowest unoccupied molecular orbital (LUMO) (out of HOMO and LUMO doublets) are important. In particular, their destructive interference with other orbitals leads to dramatic suppression of majority-spin conductance in low-symmetry configurations. For a minorityspin channel, on the contrary, the conductance is strongly enhanced when the symmetry is lowered due to an increase in hybridization strength. We believe that our results may offer a potential route for creating molecular devices with a large on-off ratio of spin polarization via quantum interference effects.PACS numbers:

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Section: Introductionmentioning

confidence: 93%

Symmetry aspects of spin filtering in molecular junctions: Hybridization and quantum interference effects

Banerjee

Mondal

et al. 2019

Phys. Rev. B

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“…1) in molecules such as porphyrins or phthalocyanines. Singlemolecule conductance measurements have indeed been performed on these systems [27][28][29], so the possibility for bias ramping has also been demonstrated already. As an observable indicating the slow decay of the ring currents, we propose to measure the photons that are emitted when these currents decay via coupling to the radiation field.…”

Section: -3mentioning

confidence: 99%

Long-lived circulating currents in strongly correlated nanorings

Schoenauer

Gergs

Schmitteckert

et al. 2019

Phys. Rev. Research

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We study the time-evolving currents flowing in an interacting ring-shaped nanostructure after a bias voltage has been switched on. The source-to-drain current exhibits the expected relaxation towards its quasistatic equilibrium value at a rate 0 reflecting the lead-induced broadening of the ring states. In contrast, the current circulating within the ring decays with a different rate , which is a rapidly decaying function of the interaction strength and thus can take values orders of magnitude below 0 . This implies the existence of a regime in which the nanostructure is far from equilibrium even though the transmitted current is already stationary. We discuss experimental setups to observe the long-lived ring transients.

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“…This field of research has considerably grown and raised the hope for more efficient devices of data storage and computing [4][5][6][7][8] . Recently, the adsorption and coupling of molecules on surfaces with layered AFM order (interlayer in AFM order while intralayer in FM order) have been used to explore spin-polarized transport and the exchange bias effect [8][9][10] . A previous study proposed that a nanoscopic giant magnetoresistance (GMR) junction with a single molecule as the nonmagnetic spacer offers the possibility to replace one of the ferromagnetic electrodes by an antiferromagnet 10 .…”

Section: Introductionmentioning

confidence: 99%

“…Recently, the adsorption and coupling of molecules on surfaces with layered AFM order (interlayer in AFM order while intralayer in FM order) have been used to explore spin-polarized transport and the exchange bias effect [8][9][10] . A previous study proposed that a nanoscopic giant magnetoresistance (GMR) junction with a single molecule as the nonmagnetic spacer offers the possibility to replace one of the ferromagnetic electrodes by an antiferromagnet 10 . The significant advantage of the above structure is that the AFM materials are ideally hard magnetic [11][12][13] , thus it is no longer necessary to use complex artificial antiferromagnets to pin the hard magnetic layer.…”

Section: Introductionmentioning

confidence: 99%

Fullerene/layered antiferromagnetic reconstructed spinterface: Subsurface layer dominates molecular orbitals’ spin-split and large induced magnetic moment

Shao

Pang

Pan³

et al. 2018

The Journal of Chemical Physics

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The interfaces between organic molecules and magnetic metals have gained increasing interest for both fundamental reasons and applications. Among them, the C/layered antiferromagnetic (AFM) interfaces have been studied only for C bonded to the outermost ferromagnetic layer [S. L. Kawahara et al., Nano Lett. 12, 4558 (2012) and D. Li et al., Phys. Rev. B 93, 085425 (2016)]. Here, via density functional theory calculations combined with evidence from the literature, we demonstrate that C adsorption can reconstruct the layered-AFM Cr(001) surface at elevated annealing temperatures so that C bonds to both the outermost and the subsurface Cr layers in opposite spin directions. Surface reconstruction drastically changes the adsorbed molecule spintronic properties: (1) the spin-split p-d hybridization involves multi-orbitals of C and top two layers of Cr with opposite spin-polarization, (2) the subsurface Cr atom dominates the C electronic properties, and (3) the reconstruction induces a large magnetic moment of 0.58 μ in C as a synergistic effect of the top two Cr layers. The induced magnetic moment in C can be explained by the magnetic direct-exchange mechanism, which can be generalized to other C/magnetic metal systems. Understanding these complex hybridization behaviors is a crucial step for molecular spintronic applications.

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Single Molecule Magnetoresistance with Combined Antiferromagnetic and Ferromagnetic Electrodes

Cited by 47 publications

References 23 publications

Symmetry aspects of spin filtering in molecular junctions: Hybridization and quantum interference effects

Symmetry aspects of spin filtering in molecular junctions: Hybridization and quantum interference effects

Long-lived circulating currents in strongly correlated nanorings

Fullerene/layered antiferromagnetic reconstructed spinterface: Subsurface layer dominates molecular orbitals’ spin-split and large induced magnetic moment

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