Theoretical and Computational Nanoscience Group

Group Leader: Stephan Roche

Main Research Lines

  • Leading-edge theoretical research on quantum transport phenomena in graphene and 2D mateirals

  • Spin dynamics and entanglement properties in Dirac matter (graphene, topological insulators)

  • Thermal transport properties and thermoelectricity

  • Predictive modelling and multiscale numerical simulation of complex nanomaterials and quantum nanodevices

In 2017 the group published the following four publications of note:

Giant spin lifetime anisotropy in graphene induced by proximity effects

Models developed by the group this year pointed to a spin lifetime anisotropy several orders of magnitude larger than the 1:1 ratio typically observed in 2D systems. Theoretically inducing a spin filter effect in graphene/TMDC heterostructures via the proximity effect, where transmission is determined by the orientation of the spins that reach it, this represents the first step to achieving direct electric-field tuning of the propagation of spins in graphene.

Valley polarised quantum transport generated by gauge fields in graphene

This year the group has also reported on the ability to simultaneously induce a bulk valley-polsarised dissipative transport and a quantum valley Hall effect in graphene by combining strain-induced gauge fields and real magnetic fields. Their results provide strong experimental basis for a fully valley-polarised device principle.

Scale-invariant large non-locality in polycrystalline graphene

Together with an experimental group at CIC-nanoGUNE, the group reported on scale-invariant non-local transport in large-scale CVD graphene under application of an external magnetic field. The work points to the existence of field-induced spin-filtered edge states whose sensitivity to grain boundaries manifests in the non-local resistance. Found to persist up to the millimetre scale, this suggests that topological Hall effects are highly influenced by the underlying structural morphology, which would limit any practical realisations.

Spin Hall effect and weak antilocalisation in graphene/transition metal dichalcogenide heterostructures

The group has performed a theoretical study of the spin Hall effect and weak antilocalisation in graphene/TMDC heterostructures, calculated using efficient real-space quantum transport methods and realistic tight-binding models parametrised from ab initio calculations. The findings provide guidelines for future experimental study at the upper limits of spin current formation and will enable full exploitation of the potential of 2D materials for spintronic applications.

Group Leader

Stephan Roche

ICREA Prof Stephan Roche
stephan.roche@icn2.cat

Prof. Stephan Roche is a theoretician with more than 25 years of experience in the study of transport theory in low-dimensional systems, including graphene, carbon nanotubes, semiconducting nanowires, organic materials and topological insulators.

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