Refined electron-spin transport model for single-element ferromagnetic systems: Application to nickel nanocontacts

Spin–Orbit Torque in Single-Molecule Junctions from ab Initio

“…In short, starting from an optimized geometry of the molecular junction obtained with the FHI-aims package, we perform a self-consistent DFT , -NEGF , cycle that accounts for the charge redistribution in the junction due to the macroscopic nature of the contacts. ,− We ensure the charge neutrality and screening the excess charge accumulated at the boundaries of the finite cluster by a self-energy model implemented in the module AITRANSS. ,, This module was recently extended to include SO coupling . Our self-consistent scheme thus expands available DFT-NEGF self-consistent cycles. ,,,− …”

Simulation of the Einstein-de Haas effect combining molecular and spin dynamics

“…Our implementation of the SLD model is applicable to combined molecular and spin dynamics of systems of arbitrary symmetry (including bulk, clusters, defect systems, etc.) It allows the modelling of a wide range of potential new systems at finite temperatures, for example: non-collinear magnetic domain walls in ferromagnetic atomic-sized contacts or wires [24][25][26], chiral spin textures in magnetic nanoparticles [27,28], skyrmions [29,30], and an atomistic description of the Barnett [2] and Barkhausen [31] effects, amongst others.…”

Electrically Controlled Bimetallic Junctions for Atomic-Scale Electronics

“…Starting with homometallic junctions, where a single wire is broken and reformed in cryogenic vacuum, Figure b presents conductance traces as a function of interelectrode displacement during stretching of Au–Au (red) and Ni–Ni (gray) junctions. The conductance drops in steps whenever the contact diameter between the electrodes is reduced, and the last plateau before junction rupture indicates the conductance of a single-atom contact. − Since the conductance characteristics can vary between different contact realizations, Figure c shows conductance histograms, based on 10,000 conductance traces, each with peaks that identify the most probable conductance during junction stretching. The repeated plateaus seen in Figure b for single-atom contacts at ∼1 G 0 for Au–Au junctions and ∼1.6 G 0 (sometimes also at ∼1.2 G 0 − ) for Ni–Ni junctions construct dominant peaks in the respective Figure c histograms ( G 0 ≅1/12.9 (kΩ) −1 is the conductance quantum).…”

“…The conductance drops in steps whenever the contact diameter between the electrodes is reduced, and the last plateau before junction rupture indicates the conductance of a single-atom contact. − Since the conductance characteristics can vary between different contact realizations, Figure c shows conductance histograms, based on 10,000 conductance traces, each with peaks that identify the most probable conductance during junction stretching. The repeated plateaus seen in Figure b for single-atom contacts at ∼1 G 0 for Au–Au junctions and ∼1.6 G 0 (sometimes also at ∼1.2 G 0 − ) for Ni–Ni junctions construct dominant peaks in the respective Figure c histograms ( G 0 ≅1/12.9 (kΩ) −1 is the conductance quantum). The ∼1 G 0 conductance of single Au–Au atomic contacts is mostly given by an almost fully open conduction channel, dominated by the s valence orbitals of Au. , The higher conductance of single Ni–Ni atomic contacts comes from several partially open conduction channels, associated with s, p, and d valence orbitals. − Other features seen at higher conductance are related to multiatomic contacts.…”

“…In both cases, this shape is ascribed to two or more populations of atomic contacts with different structures, and therefore somewhat different conductance is expected. 16 , 18 , 31 In view of Figure 3 , the voltage pulse effectiveness seems to be related to the relative hardness of the two metals, although other properties such as surface energy, intermetallic bond strength, and the tendency for alloying may also play a role. For Au–Ni junctions, the applied pulse could not overcome the strong tendency of Ni wetting by Au, whereas for Fe–Ni electromigration of atoms from both electrodes was observed.…”