Band structure and topology of magneto-spin–orbit graphene is investigated using the proposed tight-binding model that incorporates both Rashba and sublattice-resolved collinear exchange couplings in ...a generic ferrimagnetic (FIM) setting for in-plane and out-of-plane magnetization directions. The resulting band structures were analyzed for possibilities to extract the strengths of exchange and Rashba couplings from experimental spin-resolved ARPES measurements of the valley gaps and π-state spin-splittings. It was shown that the topologically trivial in-plane FIM situation admits simple expressions for these quantities, whereas the out-of-plane FIM, which admits a nontrivial band topology, is harder to analyze. The obtained topological phase diagrams for the out-of-plane FIM case show that the anomalous Hall conductance is quite stable with respect to the antiferromagnetic (AFM) interaction, which tends to interfere with the QAHE phase; moreover, the topological phase transition has a rather smooth character with respect to the AFM coupling strength.
Abstract
Polar Rashba-type semiconductor BiTeI doped with magnetic elements constitutes one of the most promising platforms for the future development of spintronics and quantum computing thanks to ...the combination of strong spin-orbit coupling and internal ferromagnetic ordering. The latter originates from magnetic impurities and is able to open an energy gap at the Kramers point (KP gap) of the Rashba bands. In the current work using angle-resolved photoemission spectroscopy (ARPES) we show that the KP gap depends non-monotonically on the doping level in case of V-doped BiTeI. We observe that the gap increases with V concentration until it reaches 3% and then starts to mitigate. Moreover, we find that the saturation magnetisation of samples under applied magnetic field studied by superconducting quantum interference device (SQUID) magnetometer has a similar behaviour with the doping level. Theoretical analysis shows that the non-monotonic behavior can be explained by the increase of antiferromagnetic coupled atoms of magnetic impurity above a certain doping level. This leads to the reduction of the total magnetic moment in the domains and thus to the mitigation of the KP gap as observed in the experiment. These findings provide further insight in the creation of internal magnetic ordering and consequent KP gap opening in magnetically-doped Rashba-type semiconductors.
ATLAS software code base is over 6 million lines organised in about 2000 packages. It makes use of some 100 external software packages, is developed by more than 400 developers and used by more than ...2500 physicists from over 200 universities and laboratories in 6 continents. To meet the challenge of configuration and building of this software, the Configuration Management Tool (CMT) is used. CMT expects each package to describe its build targets, build and environment setup parameters, dependencies on other packages in a text file called requirements, and each project (group of packages) to describe its policies and dependencies on other projects in a text project file. Based on the effective set of configuration parameters read from the requirements files of dependent packages and project files, CMT commands build the packages, generate the environment for their use, or query the packages. The main focus was on build time performance that was optimised within several approaches: reduction of the number of reads of requirements files that are now read once per package by a CMT build command that generates cached requirements files for subsequent CMT build commands; introduction of more fine-grained build parallelism at package task level, i.e., dependent applications and libraries are compiled in parallel; code optimisation of CMT commands used for build; introduction of package level build parallelism, i. e., parallelise the build of independent packages. By default, CMT launches NUMBER-OF-PROCESSORS build commands in parallel. The other focus was on CMT commands optimisation in general that made them approximately 2 times faster. CMT can generate a cached requirements file for the environment setup command, which is especially useful for deployment on distributed file systems like AFS or CERN VMFS. The use of parallelism, caching and code optimisation significantly-by several times-reduced software build time, environment setup time, increased the efficiency of multi-core computing resources utilisation, and considerably improved software developer and user experience.
Intercalation of noble metals can produce giant Rashba-type spin–orbit splittings in graphene. The spin–orbit splitting of more than 100 meV has yet to be achieved in graphene on metal or ...semiconductor substrates. Here, we report the p-type graphene obtained by Pt intercalation of zero-layer graphene on SiC substrate. The spin splitting of ∼200 meV was observed at a wide range of binding energies. Comparing the results of theoretical studies of different models with the experimental ones measured by spin-ARPES, XPS and STM methods, we concluded that inducing giant spin–orbit splitting requires not only a relatively close distance between graphene and Pt layer but also the presence of graphene corrugation caused by a non-flat Pt layer. This makes it possible to find a compromise between strong hybridization and increased spin–orbit interaction. In our case, the Pt submonolayer possesses nanometer-scale lateral ordering under graphene.
The EventIndex is the complete catalogue of all ATLAS real and simulated events, keeping the references to all permanent files that contain a given event in any processing stage; its implementation ...has been substantially revised in advance of LHC Run 3 to be able to scale to the higher production rates. The Event Picking Server automates the procedure of finding the locations of large numbers of events, extracting and collecting them into separate files. It supports different formats of events and has an elastic workflow for different input data. The convenient graphical interface of the Event Picking Server is integrated with ATLAS SSO. The monitoring system controls the performance of all parts of the service.
The influence of manganese atom intercalation on the electronic structure of graphene grown on Au/Co(0001)/W(110) and SiC(0001) substrates is experimentally studied by angle-resolved photoelectron ...spectroscopy. Dispersion dependences of the graphene π states at the
point of the Brillouin zone are obtained for both systems using ultraviolet photoelectron spectroscopy, and these dependences exhibit shifts of the Dirac cone induced by manganese intercalation followed by annealing. The structure of the near-surface layers of the systems is investigated by X-ray photoelectron spectroscopy. An analysis of the core level lines indicates the possibility of formation of a thin Mn
2
Au layer on the graphene–Mn–Au interface and a quasi-two-dimensional Mn layer under graphene on the SiC substrate. A comprehensive Raman spectroscopy study of graphene on SiC demonstrates that the buffer layer remains coupled to the substrate and does not transform into an additional graphene layer after the Mn intercalation of this system. After intercalation, the amount of lattice defects in graphene increases.
Effect of magnetization generated by synchrotron or laser radiation in magnetically-doped and pristine topological insulators (TIs) is presented and analyzed using angle-resolved photoemission ...spectroscopy. It was found that non-equal photoexcitation of the Dirac cone (DC) states with opposite momenta and spin orientation indicated by the asymmetry in photoemission intensity of the DC states is accompanied by the k
-shift of the DC states relative to the non-spin-polarized conduction band states located at k
= 0. We relate the observed k
-shift to the induced surface in-plane magnetic field and corresponding magnetization due to the spin accumulation. The direction of the DC k
-shift and its value are changed with photon energy in correlation with variation of the sign and magnitude of the DC states intensity asymmetry. The theoretical estimations describe well the effect and predict the DC k
-shift values which corroborate the experimental observations. This finding opens new perspectives for effective local magnetization manipulation.
Software packaging is indispensable part of build and prerequisite for deployment processes. Full ATLAS software stack consists of TDAQ, HLT, and Offline software. These software groups depend on ...some 80 external software packages. We present tools, package PackDist, developed and used to package all this software except for TDAQ project. PackDist is based on and driven by CMT, ATLAS software configuration and build tool, and consists of shell and Python scripts. The packaging unit used is CMT project. Each CMT project is packaged as several packages—platform dependent (one per platform available), source code excluding header files, other platform independent files, documentation, and debug information packages (the last two being built optionally). Packaging can be done recursively to package all the dependencies. The whole set of packages for one software release, distribution kit, also includes configuration packages and contains some 120 packages for one platform. Also packaged are physics analysis projects (currently 6) used by particular physics groups on top of the full release. The tools provide an installation test for the full distribution kit. Packaging is done in two formats for use with the Pacman and RPM package managers. The tools are functional on the platforms supported by ATLAS—GNU/Linux and Mac OS X. The packaged software is used for software deployment on all ATLAS computing resources from the detector and trigger computing farms, collaboration laboratories computing centres, grid sites, to physicist laptops, and CERN VMFS and covers the use cases of running all applications as well as of software development.
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