Circuit-model analysis for spintronic devices with chiral molecules as spin injectors

Yang, Xueyao; Bosma, Tom; Wees, B. J. van; Wal, Caspar H. van der

doi:10.1103/physrevb.99.214428

Cited by 4 publications

(2 citation statements)

References 57 publications

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“…In the Landauer transport formulation, a different type of time-reversal symmetry breaking arises from the fact that the molecule in a molecular junction is an open system connected to electrodes acting as reservoirs. A formulation using a circuit-model analysis − has recently appeared in the literature, where the claim is made that spin polarization cannot be detected in two-terminal devices. This result is valid only if many-body effects are omitted and if the self-energy term in the Landauer–Büttiker formulation is neglected, which is not the case here.…”

Section: The Link Between Chirality-dependent Spin Polarization and T...mentioning

confidence: 99%

Insight into the Origin of Chiral-Induced Spin Selectivity from a Symmetry Analysis of Electronic Transmission

Zöllner

Varela

Medina

et al. 2020

J. Chem. Theory Comput.

126

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The chiral-induced spin selectivity (CISS) effect, which describes the spin-filtering ability of diamagnetic structures like DNA or peptides having chiral symmetry, has emerged in the past years as the central mechanism behind a number of important phenomena, like long-range biological electron transfer, enantiospecific electrocatalysis, and molecular recognition. Also, CISS-induced spin polarization has a considerable promise for new spintronic devices and the design of quantum materials. The CISS effect is attributed to spin–orbit coupling, but a sound theoretical understanding of the surprising magnitude of this effect in molecules without heavy atoms is currently lacking. We are taking an essential step into this direction by analyzing the importance of imaginary terms in the Hamiltonian as a necessary condition for nonvanishing spin polarization in helical structures. On the basis of first-principles calculations and analytical considerations, we perform a symmetry analysis of the key quantities determining transport probabilities of electrons of different spin orientations. These imaginary terms originate from the spin–orbit coupling, and they preserve the Hermitian nature of the Hamiltonian. Hence, they are not related to the breaking of time-reversal symmetry resulting from the fact that molecules are open systems in a junction. Our symmetry analysis helps to identify essential constraints in the theoretical description of the CISS effect. We further draw an analogy with the appearance of imaginary terms in simple models of barrier scattering, which may help understanding the unusually effective long-range electron transfer in biological systems.

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Section: The Link Between Chirality-dependent Spin Polarization and T...mentioning

confidence: 99%

Insight into the Origin of Chiral-Induced Spin Selectivity from a Symmetry Analysis of Electronic Transmission

Zöllner

Varela

Medina

et al. 2020

J. Chem. Theory Comput.

126

View full text Add to dashboard Cite

show abstract

“…In the Landauer transport formulation, a different type of time-reversal symmetry breaking arises from the fact that the molecule in a molecular junction is an open system connected to electrodes acting as reservoirs. A formulation using a circuit-model analysis 45 has recently appeared in the literature, where the claim is made that spin polarization cannot be detected in two-terminal devices. This result is valid only if the self-energy term in the Landauer-Buttiker formulation is neglected, which is not the case here.…”

Section: Symmetry Breaking By Imaginary Terms Introduced By Spinorbitmentioning

confidence: 99%

Chiral-Induced Spin Selectivity: A Symmetry Analysis of Electronic Transmission

Zöllner

Varela

Medina

et al. 2019

Preprint

View full text Add to dashboard Cite

The chiral-induced spin selectivity (CISS) effect, which describes the spin-filtering ability of diamagnetic structures like DNA or peptides having chiral symmetry, has emerged in the past years as the central mechanism behind a number of important phenomena, like long-range biological electron transfer, enantiospecific electrocatalysis, and molecular recognition. Also, CISS-induced spin polarization has a considerable promise for new spintronic devices and the design of quantum materials. The CISS effect is attributed to spin–orbit coupling, but a sound theoretical understanding of the surprising magnitude of this effect in molecules without heavy atoms is currently lacking. We are taking an essential step into this direction by analyzing the importance of imaginary terms in the Hamiltonian as a necessary condition for non-vanishing spin polarization in helical structures. Based on first-principles calculations and analytical considerations, we perform a symmetry analysis of the key quantities determining transport probabilities of electrons of different spin orientations. These imaginary terms originate from the spin–orbit coupling, and they preserve the Hermitian nature of the Hamiltonian. Hence, they are not related to the breaking of time-reversal symmetry resulting from the fact that molecules are open systems in a junction. Our symmetry analysis helps to identify essential constraints in the theoretical description of the CISS effect. We further draw an analogy with the appearance of imaginary terms in simple models of barrier scattering, which may help understanding the unusually effective long-range electron transfer in biological systems.<br>

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Chiral-induced spin selectivity in the formation and recombination of radical pairs: cryptochrome magnetoreception and EPR detection

Luo

Hore

2021

New J. Phys.

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That the rates and yields of reactions of organic radicals can be spin dependent is well known in the context of the radical pair mechanism (RPM). Less well known, but still well established, is the chiral-induced spin selectivity (CISS) effect in which chiral molecules act as spin filters that preferentially transmit electrons with spins polarized parallel or antiparallel to their direction of motion. Starting from the assumption that CISS can arise in electron transfer reactions of radical pairs, we propose a simple way to include CISS in conventional models of radical pair spin dynamics. We show that CISS can (a) increase the sensitivity of radical pairs to the direction of a weak external magnetic field, (b) change the dependence of the magnetic field effect on the reaction rate constants, and (c) destroy the field-inversion symmetry characteristic of the RPM. We argue that CISS polarization effects could be observable by EPR (electron paramagnetic resonance) of oriented samples either as differences in continuous wave, time-resolved spectra recorded with the spectrometer field parallel or perpendicular to the CISS quantization axis or as signals in the in-phase channel of an out-of-phase ESEEM (electron spin echo envelope modulation) experiment. Finally we assess whether CISS might be relevant to the hypothesis that the magnetic compass of migratory songbirds relies on photochemically-formed radical pairs in cryptochrome flavoproteins. Although CISS effects offer the possibility of evolving a more sensitive or precise compass, the associated lack of field-inversion symmetry has not hitherto been observed in behavioural experiments. In addition, it may no longer be safe to assume that the observation of a polar magnetic compass response in an animal can be used as evidence against a radical pair sensory mechanism.

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Circuit-model analysis for spintronic devices with chiral molecules as spin injectors

Cited by 4 publications

References 57 publications

Insight into the Origin of Chiral-Induced Spin Selectivity from a Symmetry Analysis of Electronic Transmission

Insight into the Origin of Chiral-Induced Spin Selectivity from a Symmetry Analysis of Electronic Transmission

Chiral-Induced Spin Selectivity: A Symmetry Analysis of Electronic Transmission

Chiral-induced spin selectivity in the formation and recombination of radical pairs: cryptochrome magnetoreception and EPR detection

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