Search

Spin-orbit coupling (SOC) is pivotal for various fundamental spin-dependent phenomena in solids and their technological applications. In semiconductors, these phenomena have been so far studied in relatively weak electron-electron interaction regimes, where the single electron picture holds. However, SOC can profoundly compete against Coulomb interaction, which could lead to the emergence of unconventional electronic phases. Since SOC depends on the electric field in the crystal including contributions of itinerant electrons, electron-electron interactions can modify this coupling. Here we demonstrate the emergence of theSOC effect in a high-mobility two-dimensional electron system in a simple band structure MgZnO/ZnO semiconductor. This electron system alsofeatures strong electron-electron interaction effects. By changing the carrier density with Mg-content, we tune the SOC strength and achieve its interplay with electron-electron interaction. These systems pave a way to emergent spintronic phenomena in strong electron correlation regimes and to the formation of quasiparticles with the electron spin strongly coupled to the density.

Spin-orbit coupling (SOC) is pivotal for various fundamental spin-dependent phenomena in solids and their technological applications. In semiconductors, these phenomena have been so far studied in relatively weak electron-electron interaction regimes, where the single electron picture holds. However, SOC can profoundly compete against Coulomb interaction, which could lead to the emergence of unconventional electronic phases. Since SOC depends on the electric field in the crystal including contributions of itinerant electrons, electron-electron interactions can modify this coupling. Here we demonstrate the emergence of theSOC effect in a high-mobility two-dimensional electron system in a simple band structure MgZnO/ZnO semiconductor. This electron system alsofeatures strong electron-electron interaction effects. By changing the carrier density with Mg-content, we tune the SOC strength and achieve its interplay with electron-electron interaction. These systems pave a way to emergent spintronic phenomena in strong electron correlation regimes and to the formation of quasiparticles with the electron spin strongly coupled to the density.

Spin-orbit coupling (SOC) is pivotal for various fundamental spin-dependent phenomena in solids and their technological applications. In semiconductors, these phenomena have been so far studied in relatively weak electron-electron interaction regimes, where the single electron picture holds. However, SOC can profoundly compete against Coulomb interaction, which could lead to the emergence of unconventional electronic phases. Since SOC depends on the electric field in the crystal including contributions of itinerant electrons, electron-electron interactions can modify this coupling. Here we demonstrate the emergence of theSOC effect in a high-mobility two-dimensional electron system in a simple band structure MgZnO/ZnO semiconductor. This electron system alsofeatures strong electron-electron interaction effects. By changing the carrier density with Mg-content, we tune the SOC strength and achieve its interplay with electron-electron interaction. These systems pave a way to emergent spintronic phenomena in strong electron correlation regimes and to the formation of quasiparticles with the electron spin strongly coupled to the density.

A flat band in fermionic system is a dispersionless single-particle state with a diverging effective mass and nearly zero group velocity. These flat bands are expected to support exotic properties in the ground state, which might be important for a wide range of promising physical phenomena. For many applications, it is highly desirable to have such states in Dirac materials, but so far they have been reported only in some nonmagnetic Dirac systems. In this paper, we propose a realization of topologically protected spin-polarized flat bands generated by domain walls in planar magnetic topological insulators. Using first-principles material design, we suggest a family of intrinsic antiferromagnetic topological insulators with an in-plane sublattice magnetization and high Néel temperature. Such systems can host domain walls in a natural manner. For these materials, we demonstrate the existence of spin-polarized flat bands in the vicinity of the Fermi level and discuss their properties and potential applications.

We analyze shot noise in a magnetic tunnel junction with a two-level quantum dot attached to the magnetic electrodes. The considerations are limited to the case when some transport channels are suppressed at low temperatures. Coupling of the two dot's levels to the electrodes are assumed to be generally different and also spin dependent. To calculate the shot noise we apply the approach based on the full counting statistics. The approach is used to account for experimental data obtained in magnetic tunnel junctions with organic barriers. The experimentally observed Fano factors correspond to the super-Poissonian statistics, and also depend on relative orientation of the electrodes' magnetic moments. We have also calculated the corresponding spin shot noise, which is associated with fluctuations of spin current.

We discuss the role of spin-flip scattering of electrons from the magnetized edges in graphene nanoribbons. The spin-flip scattering is associated with strong fluctuations of the magnetic moments at the edge. Using the Boltzmann equation approach, which is valid for not too narrow nanoribbons, we calculate the spin-relaxation time in the case of Berry-Mondragon and zigzag graphene edges. We also consider the case of ballistic nanoribbons characterized by very long momentum relaxation time in the bulk, when the main source of momentum and spin relaxation is the spin-dependent scattering at the edges. We found that in the case of zigzag edges, an anomalous spin diffusion is possible, which is related to very weak spin-flip scattering of electrons gliding along the nanoribbon edge. © 2014 American Physical Society.

We consider a system consisting of a topological insulator with an array of magnetic adatoms interacting with the surface states of electrons. We find that the indirect coupling of the magnetic impurities results in a ferromagnetic ordering of the magnetic moments and is also responsible for the unusual linear dispersion of the surface magnons. We also show that the interaction of magnons with surface electrons essentially renormalizes the electron energy spectrum. The renormalized spectrum is nonlinear and can be characterized by a negative effective mass of electrons and holes for any k≠0. The electron velocity near the Dirac point depends on the electron-magnon coupling. © 2014 American Physical Society.

We report on dependence of conductance and tunnelling magnetoresistance on bias voltage at different temperatures down to 2 K in Co|Al[subscript 2]O[subscript 3](10 Å)|Si(δ)|Al[subscript 2]O[subscript 3](2 Å)|Permalloy magnetic tunnel junctions. Complementary low frequency noise measurements are used to understand the conductance results. The obtained data indicate the breakdown of the Coulomb blockade for thickness of the asymmetric silicon layer exceeding 1.2 Å. The crossover in the conductance, the dependence of the tunneling magnetoresistance with the bias voltage and the noise below 80 K correspond to one monolayer coverage. Interestingly, the zero bias magnetoresistance remains nearly unaffected by the presence of the silicon layer. The proposed model uses Larkin-Matveev approximation of tunneling through a single impurity layer generalized to three-dimensional case and takes into account the variation of the barrier shape with the bias voltage. The main difference is the localization of all the impurity levels within a single atomic layer. In the high thickness case, up to 1.8 Å, we have introduced a phenomenological parameter, which reflects the number of single levels on the total density of silicon atoms., United States. Office of Naval Research (Grant No. N00014-06-1-0235), National Science Foundation (U.S.) (Grant No. DMR-0504158), Madrid (Spain : Region) (Grant No. P2009/MAT-1726), Spain. Ministerio de Ciencia e Innovación (MICINN) (Grant No. MAT2006-07196), Spain. Ministerio de Ciencia e Innovación (MICINN) (Grant No. MAT2009- 10139), Spain. Ministerio de Ciencia e Innovación (MICINN) (Consolider Grant No. CSD2007-00010), European Science Foundation. EUROCORES Programme (Grant No. 05-FONE-FP-010-SPINTRA), European Science Foundation. Arrays of Quantum Dots adn Josephson Junctions (AQDJJ) programme, Fundação para a Ciência e a Tecnologia (FCT) (Grant PTDC/FIS/70843/2006), Poland. Ministry of Science and Higher Education

We report on dependence of conductance and tunnelling magnetoresistance on bias voltage at different temperatures down to 2 K in Co|Al[subscript 2]O[subscript 3](10 Å)|Si(δ)|Al[subscript 2]O[subscript 3](2 Å)|Permalloy magnetic tunnel junctions. Complementary low frequency noise measurements are used to understand the conductance results. The obtained data indicate the breakdown of the Coulomb blockade for thickness of the asymmetric silicon layer exceeding 1.2 Å. The crossover in the conductance, the dependence of the tunneling magnetoresistance with the bias voltage and the noise below 80 K correspond to one monolayer coverage. Interestingly, the zero bias magnetoresistance remains nearly unaffected by the presence of the silicon layer. The proposed model uses Larkin-Matveev approximation of tunneling through a single impurity layer generalized to three-dimensional case and takes into account the variation of the barrier shape with the bias voltage. The main difference is the localization of all the impurity levels within a single atomic layer. In the high thickness case, up to 1.8 Å, we have introduced a phenomenological parameter, which reflects the number of single levels on the total density of silicon atoms., United States. Office of Naval Research (Grant No. N00014-06-1-0235), National Science Foundation (U.S.) (Grant No. DMR-0504158), Madrid (Spain : Region) (Grant No. P2009/MAT-1726), Spain. Ministerio de Ciencia e Innovación (MICINN) (Grant No. MAT2006-07196), Spain. Ministerio de Ciencia e Innovación (MICINN) (Grant No. MAT2009- 10139), Spain. Ministerio de Ciencia e Innovación (MICINN) (Consolider Grant No. CSD2007-00010), European Science Foundation. EUROCORES Programme (Grant No. 05-FONE-FP-010-SPINTRA), European Science Foundation. Arrays of Quantum Dots adn Josephson Junctions (AQDJJ) programme, Fundação para a Ciência e a Tecnologia (FCT) (Grant PTDC/FIS/70843/2006), Poland. Ministry of Science and Higher Education