5 research outputs found
When Molecular Dimerization Induces Magnetic BiâStability at the MetalâOrganic Interface
Abstract 2D metalâorganic frameworks have been recently proposed as a flexible platform for realizing new functional materials including quantum phases. Here, we present a method to create metalâorganic dimer complexes by onâsurface assembly on a metal substrate using lowâtemperature scanning tunneling microscopy (STM) and spectroscopy (STS). We demonstrate that a dimer of MnâPhthalocyanine (MnPc)2 on a Ag(111) surface can be switched between two stable configurations upon a small conformational change controlled by STM manipulation. By means of densityâfunctional theory calculations, it is found that the two conformations correspond to an antiferromagnetic (AFM) and a ferromagnetic (FM) state respectively. Directly coordinated Mn atoms of the dimer lead to an AFMâcoupling whereas indirectly coordinated (shifted) Mn atoms lead to a FMâcoupling. Rarely seen in a molecularâdimers with transitionâmetal atoms, the FMâAFMâFM transition is thus readily onâsurface accessible. Furthermore, the two configurations of the switch are easily identified by their Kondo states, opening interesting routes in terms of both, writing (FM versus AFM states) and reading. These results pave the experimental route toward dimerâbased materials with complex magnetic structures of potential interest for application in spintronics, logics and computing
Fluorinated Phthalocyanine Molecules on Ferromagnetic Cobalt: A Highly Polarized Spinterface
International audienc
Quantum advantage in a spintronic engine with coherently coupled ultrafast strokes using molecular superexchange
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, implementing work-producing quantum resources
has required atomic engines driven by external laser and microwave energy
sources We propose a spin electronic implementation that operates autonomously.
Our concept heuristically deploys several known quantum resources upon placing
a quantum-entangled chain of spin qubits formed by the Co centers of
phthalocyanine (Pc) molecules between electron-spin selecting Fe/C60
interfaces. Density functional calculations reveal that transport fluctuation
strokes across the interfaces can stabilize spin coherence on the Co
paramagnetic centers, which host spin swap engine strokes. Across solid-state
vertical molecular nanojunctions, we measure large enduring dc current
generation, sizeable output power above room temperature, and two quantum
thermodynamical signatures. The Fe/C60 interface's record 89% spin polarization
also enables a spintronic feedback and control over the flow and direction of
charge current. Beyond these first results, further research into spintronic
quantum engines, and retooling the spintronic-based information technology
chain7, could help accelerate the transition to clean energy.Comment:
Encoding Information on the Excited State of a Molecular Spin Chain
International audienceThe quantum states of nano-objects can drive electrical transport properties across lateral and local-probe junctions. This raises the prospect, in a solid-state device, of electrically encoding information at the quantum level using spinflip excitations between electron spins. However, this electronic state has no defined magnetic orientation and is short-lived. Using a novel vertical nanojunction process, these limitations are overcome and this steady-state capability is experimentally demonstrated in solid-state spintronic devices. The excited quantum state of a 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. This low-voltage control over a spin chain's quantum state and spintronic contribution lay a path for transmitting spin wave-encoded information across molecular layers in devices. It should also stimulate quantum prospects for the antiferromagnetic spintronics and oxides electronics communities