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Communication Dans Un Congrès Année : 2023

Spintronic encoding of quantum information onto individual atoms within solid-state junctions

Résumé

An electrical current that flows across individual atoms or molecules can generate exotic quantum-based behavior, from memristive effects to Coulomb blockade [1] and the promotion of quantum excited states [2]. These fundamental effects typically appear one at a time in model junctions built using atomic tip or lateral techniques. So far, however, a viable industrial pathway for such devices has been lacking. We first present experiments on vertical magnetic molecular nanojunctions [3]. The electrically excited quantum state of the spin chain formed by Co phthalocyanine molecules coupled to a ferromagnetic electrode constitutes a distinct magnetic unit endowed with a coercive field. This generates a specific steady-state magnetoresistance trace that is tied to the spin-flip conductance channel, and is opposite in sign to the ground state magnetoresistance term, as expected from spin excitation transition rules. The experimental 5.9 meV thermal energy barrier between the ground and excited spin states is confirmed by density functional theory, in line with macrospin phenomenological modeling of magnetotransport results. We have also studied ‘industrializable’ magnetic tunnel junctions with a MgO barrier containing C atoms [4]. We demonstrate that the effective nanotransport path [5] due to the resulting localized paramagnetic [6] states involves individual C atoms. Their discrete energy levels promote Coulomb blockade effects that can be reproducibly shifted in energy by charging events on neighboring C atoms. The tunnel coupling between these transport and environmental carbon atoms promotes quantum interference effects. Spin-polarized transport induces spin accumulation that lifts the spin degeneracy of the unpaired C electron in MgO. This leads to a voltage shift in Coulomb peaks and quantum interference effects between the datasets in the MTJ’s P and AP magnetic states. Spin accumulation also accounts for the huge enhancement of the spintronic performance when a Coulomb peak is memristively controlled. References [1] P. Gehring, J. M. Thijssen, and H. S. J. van der Zant, Single-Molecule Quantum-Transport Phenomena in Break Junctions, Nature Reviews Physics 1, 381 (2019). [2] A. J. Heinrich, W. D. Oliver, L. M. K. Vandersypen, A. Ardavan, R. Sessoli, D. Loss, A. B. Jayich, J. Fernandez-Rossier, A. Laucht, and A. Morello, Quantum-Coherent Nanoscience, Nat. Nanotechnol. 16, 1318 (2021). [3] K. Katcko et al., Encoding Information on the Excited State of a Molecular Spin Chain, Advanced Functional Materials 2009467 (2021). [4] M. Lamblin and et al., Encoding Information onto the Charge and Spin State of a Paramagnetic Atom Using MgO Tunnelling Spintronics, In Preparation. (2023). [5] M. Studniarek et al., Probing a Device’s Active Atoms, Advanced Materials 29, 1606578 (2017). [6] K. Katcko et al., Spin-Driven Electrical Power Generation at Room Temperature, Communications Physics 2, 116 (2019).
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Dates et versions

hal-04274814 , version 1 (08-11-2023)

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  • HAL Id : hal-04274814 , version 1

Citer

Martin Bowen. Spintronic encoding of quantum information onto individual atoms within solid-state junctions. EMRS Fall Meeting 2023, Sep 2023, Warsaw, Poland. ⟨hal-04274814⟩

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