arXiv subjects

Loic Joly

Publications and source records attributed to Loic Joly.

3 recordsLinked to original sources

arXiv2023

Encoding information onto the charge and spin state of a paramagnetic atom using MgO tunnelling spintronics

An electrical current that flows across individual atoms can generate exotic quantum transport signatures in model junctions built using atomic tip or lateral techniques. So far, however, a viable industrial pathway for atom-driven devices has been lacking. Here, we demonstrate that a commercialized device platform can fill this nanotechnological gap. According to conducting tip atomic force microscopy, inserting C atoms into the MgO barrier of a magnetic tunnel junction generates nanotransport paths. Within magnetotransport experiments, this results in quantum interferences, and in Pauli spin blockade effects linked to tunneling magnetoresistance peaks that can be electrically controlled. We report an additional persistent memory effect that we attribute to the charging of a single "gating" C atom that is adjacent to a single C atom forming the microscale junction's effective nanotranport path. Local magnetometry experiments confirm the secondary role of magnetic stray fields on the C atoms. Our results show that, to exhibit atom-level properties, a device need not be nanoscaled, and position MgO tunneling spintronics as a promising platform to industrially implement quantum technologies.

cond-mat.mes-hall↗

arXiv2020

Quantum advantage in a molecular spintronic engine that harvests thermal fluctuation energy

Recent theory and experiments have showcased how to harness quantum mechanics to assemble heat/information engines with efficiencies that surpass the classical Carnot limit. So far, this has required atomic engines that are driven by cumbersome external electromagnetic sources. Here, using molecular spintronics, we propose an implementation that is both electronic and autonomous. Our spintronic quantum engine heuristically deploys several known quantum assets by having a chain of spin qubits formed by the paramagnetic Co centers of phthalocyanine (Pc) molecules electronically interact with electron-spin selecting Fe/C60 interfaces. Density functional calculations reveal that transport fluctuations across the interface can stabilize spin coherence on the Co paramagnetic centers, which host spin flip processes. Across vertical molecular nanodevices, we measure enduring dc current generation, output power above room temperature, two quantum thermodynamical signatures of the engine's processes, and a record 89% spin polarization of current across the Fe/C60 interface. It is crucially this electron spin selection that forces, through demonic feedback and control, charge current to flow against the built-in potential barrier. Further research into spintronic quantum engines, insight into the quantum information processes within spintronic technologies, and retooling the spintronic-based information technology chain, could help accelerate the transition to clean energy.

cond-mat.mes-hall↗

arXiv2018

Linking electronic transport through a spin crossover thin film to the molecular spin state using X-ray absorption spectroscopy operando techniques

One promising route toward encoding information is to utilize the two stable electronic states of a spin crossover molecule. However, while this property is clearly manifested in transport across single molecule junctions, evidence linking charge transport across a solid-state device to the molecular film's spin state has thus far remained indirect. To establish this link, we deploy materials-centric and device-centric operando experiments involving X-ray absorption spectroscopy. We find a correlation between the temperature dependencies of the junction resistance and the Fe spin state within the device's Fe(bpz)2(phen) molecular film. We also factually observe that the Fe molecular site mediates charge transport. Our dual operando studies reveal that transport involves a subset of molecules within an electronically heterogeneous spin crossover film. Our work confers an insight that substantially improves the state-of-the-art regarding spin crossover-based devices, thanks to a methodology that can benefit device studies of other next-generation molecular compounds.

physics.app-ph↗