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Interaction phenomena in novel materials

Final Report Summary - INTERNOM (Interaction phenomena in novel materials)

One of the main goals of the project "Interaction phenomena in Novel Materials" (InterNoM) was to combine the efforts of scientific teams from the Netherlands, Britain, Germany, and Russia in achieving the following objectives:
● to develop fundamentals of the different types of interactions in graphene;
● to reveal and analyse various quantum and semiclassical transport phenomena in graphene and topological insulators;
● to create a theoretical basis for using graphene-based structures in THz nanoelectronics.
In the course of the project there have been a remarkable progress in achieving these objectives. The planned research has been fully conducted and a number of novel and unexpected results have been obtained. Overall the project appeared to be very successful.
During the project implementation we performed the following work:
We developed a hydrodynamic description of transport properties in graphene-based systems. We used the developed theory to explain a number of experiments in single- and double-layer graphene systems. In addition we studied magnetotransport in two-component electron-hole systems and transport in a system composed of graphene aligned with a hexagonal boron nitride substrate. We calculated the longitudinal conductivity of graphene at the Dirac point in a strong magnetic field and in a presence of two types of short-range scatterers: adatoms and "scalar" impurities. We developed variable-phase method in order to analyze zero-energy bound states. We studied the anomalous Hall effect that arises in systems with both spin-orbit coupling and magnetization. We studied a number of promising approaches to generate terahertz radiation. We studied the quantum transport in HgTe/HgCdTe quantum wells. We studied quantum interference effects in a 2D chiral metal (bipartite lattice) with vacancies. We applied functional Keldysh theory to investigate spin-orbit torques in metallic disordered two-dimensional Rashba ferromagnets. We developed a theory of the Majorana representation of spin operators. We developed a theory of giant Coulomb drag between two closely positioned graphene monolayers. We analyzed the transport properties of an Aharonov-Bohm interferometer made of a single-channel quantum ring. We explored the weak-strong-coupling Bose-Fermi duality in a model of a single-channel integer or fractional quantum Hall edge state with a finite-range interaction. We explored the low-frequency noise of interacting electrons in a one-dimensional structure with counter-propagating modes.

We have found exact solutions to the 2D Dirac equation for the 1DPoschl-Teller potential, which contains an asymmetry term. We developed a minimal model exhibiting effective couplings between four Majorana zero modes - the non-uniform Ising-Kitaev chain, containing two "topological" regions separated by a "trivial" region. We have investigated the electronic and optical properties of single-layer phosphorene quantum dots with various shapes, sizes, and edge types subjected to an external electric field. We have studied pair states in 1D Dirac systems. We have investigated localization effects induced by spatial modulations of the Fermi velocity in 2D Dirac materials. We have developed an analytical tight-binding theory of the optical properties of graphene nanoribbons with zigzag edges and found optical selection rules for such ribbons. We studied Coulomb drag between two helical edges with broken spin-rotational symmetry. We have developed a theory of heat transfer in a 2D two-component system consisting of electrons and holes with the same concentrations. The charge-carrier density, temperature distributions, and electric-current densities have been calculated by solving the balance equations. Combining the Boltzmann kinetic equation with sample electrostatics, we develop a microscopic theory of magnetotransport in two and three spatial dimensions. We demonstrated that the compensated Hall effect in confined geometry is always accompanied by electron-hole recombination near the sample edges and at large-scale inhomogeneities. As the result, classical edge currents may dominate the resistance in the vicinity of charge compensation. We demonstrated that a circularly polarized radiation induces the diamagnetic, helicity-sensitive dc current in a ballistic nanoring. This current is dramatically enhanced in the vicinity of plasmonic resonances. We have developed the theory of quantum transport and magnetoconductivity for two-dimensional electrons with an arbitrarily large, linear-in-momentum Rashba or Dresselhaus spin-orbit splitting. We have predicted a nonsaturating linear magnetoresistance in charge-compensated bilayer graphene in a temperature range from 1.5 to 150 K. The prediction was confirmed by experiment. We have studied the motion of an electron in a free standing graphene under the influence of flexural vibrations with different correlation functons. We have stidied magnetotransport in single layer graphene in a large parallel magnetic field and found that the effects of Zeeman splitting are fully masked by electrostatic potential fluctuations at charge neutrality.