Two-dimensional networks of spins are fascinating both for the study of low-dimensional magnetism and for the prospects in molecular quantum devices. Here we have fabricated a 2D supramolecular lattice consisting of manganese phthalocyanine (MnPc) on Ag(111). Lowtemperature scanning tunneling microscopy/spectroscopy (STM/STS) and density functional theory (DFT) calculations are applied to study the magnetic state and the electronic structure evolution from the isolated molecule to the fully 2D self-assembled molecular network. It is found that the magnetic Kondo resonance on the Mn ion is not affected by the increasing molecular 2D coordination, whereas an unusual extension of the Kondo resonance over the MnPc molecules provides additional evidence for the magnetic polarization of the ligand. Both STS and ab initio electronic structure calculations demonstrate the formation of an underscreened 2D Kondo lattice of MnPc molecules that are prone to long-range antiferromagnetic order. A checkerboard configuration of the molecular spin density is formed above the Ag(111) surface as a result of an indirect exchange interaction mediated by the silver substrate.

Spin-resolved photoemission spectroscopy experiments are performed on perfluorinated Co-phthalocyanine (F 16 CoPc) deposited onto ferromagnetic Co(001) to examine how doping (here with fluorine) of an organic semiconductor influences the interfacial electronic properties, and whether the formation of highly spin-polarized interface states is possible. It is found that this later property, initially reported for the non-fluorinated Pc, is also present for the fluorinated system Co/F 16 CoPc. This result shows that doping an organic semiconductor, which is an important and effective method to tailor the electronic transport properties of the molecules, does not inhibit the presence of a highly polarized spinterface.

The 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 spin‐flip 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.