Grain boundary segregation occurs during thermal treatment and results in formation of thin layers of different composition compared to the base material which is spread continuously throughout a device. This often results in loss of cohesion in these regions and in embrittlement of the device which is extremely dangerous in applications. The book describes in detail the grain boundary segregation in metallic materials from theoretical point of view through its...
Magnetoelectric multiferroics are materials, which exhibit simultaneously magnetic and ferroelectric order. Unfortunately, there are only few multiferroics in nature and they have usually low critical temperatures and their magnetoelectric coupling is small. In this paper we first time experimentally demonstrated that new "artificial" multiferroics can be prepared using the strain in the thin films. We proved that originally antiferromagnetic and paraelectric EuTiO...
The first paper published by the ATLAS Collaboration using an early LHC data. Properties of ordinary proton-proton interactions were measured at center of mass energy of √s = 900 GeV. The data are important for tuning models of soft, low momentum transfer physics. These events constitute a background to the short-distance scale physics which is the main focus of ATLAS and CMS. Understanding this background is important for full exploration of discovery...
60 years after the discovery of a transistor its operation is still based on the same physical principle of electrical manipulation and detection of electron’s charge in a semiconductor. Since we are quickly approaching the ultimate down-scaling limit it is now an eminent task to establish new physical principles of transistor operation. One extensively studied possibility is utilizing the second basic attribute of electron which is its spin. Theoretical proposal of...
This review summarizes recent first-principles investigations of the electronic structure and magnetism of dilute magnetic semiconductors (DMSs) use in spintronics. Details of the electronic structure of transition-metal-doped III-V and II-VI semiconductors are described, especially how the electronic structure couples to the magnetic properties of an impurity. In addition, the underlying mechanism of the ferromagnetism in DMSs is investigated from the electronic...
We study theoretically the electronic states in a 5d transition metal oxide Na2IrO3, in which both the spin-orbit interaction and the electron correlation play crucial roles. A tight-binding model analysis together with the first-principles band structure calculation predicts that this material is a layered quantum spin Hall system. Because of the electron correlation, an antiferromagnetic order first develops at the edge, and later inside the...
This extensive article was written under the guidance of FZU group and it describes the world largest Fluorescence detector system. The group initiated the very idea of writing the paper, contributed with a chapter on the optical setup, organization of various international groups, text editing, correspondence with referees, chapter on detector operation, etc. The article describes the components of the fluorescence detector including its optical system, the design of the...
Silicon nanocrystals are an extensively studied light-emitting material due to their inherent biocompatibility and compatibility with silicon-based technology. Although they might seem to fall behind their rival, namely, direct band gap based semiconductor nanocrystals, when it comes to the emission of light, room for improvement still lies in the exploitation of various surface passivations. In this paper, we report on an original way, taking place at room temperature...
We have investigated by means of neutron diffraction and magnetic measurements the particle size effects on the structure and low-temperature spin arrangement in so-called half doped manganites. The study shows that the Mn3+/Mn4+charge ordering and CE-type antiferromagnetic structure characteristic for bulk are completely suppressed when particle size is decreased down to 20 nm, and a ferromagnetic state is stabilized instead. The reason is...
Modulated phases occur in numerous functional materials like giant ferroelectrics and magnetic shape-memory alloys. For the first time we showed that Ni-Mn-Ga modulated martensite exhibiting the giant magnetically induced strain (magnetic shape memory effect) can be considered as an adaptive phase which profoundly changes the perception of modulated phases in this materials and it is important for understanding of the effect. We investigated the coexistence of austenite...
Dye-sensitized semiconductors are promising materials for applications in Grätzel solar cells. Here we are interested in the electron injection into the semiconductor and the initial phase of the electron transport towards the anode. We show that the charge transport in the nanostructured active solar cell material can be very different from that in nonsensitized semiconductors. For ZnO an electron-cation complex is formed within 5 ps which causes fast charge...
The paper provides first systematic analysis of properties of all mechanically compatible and electrically neutral domain walls in tetragonal, orthorhombic, and rhombohedral ferroelectric phases of BaTiO3. Polarization and strain profiles within domain walls are calculated. Domain-wall thicknesses and energy densities are estimated for all mechanically compatible and electrically neutral domain-wall species in the entire temperature range of ferroelectric...
We suggested using strong internal electric field in multiferroic Eu0.5Ba0.5TiO3 for the search of permanent electric dipole moment (EDM) of the electron. According to standard model of particles its value should be of order of 10–40 e.cm. Recently it has been shown that spontaneous violation of charge parity symmetry is much larger then it follows from the standard model, therefore this model needs an extension. New...
We analyzed microscopically the valence and impurity band models of ferromagnetic (Ga,Mn)As. We found that the tight-binding Anderson approach with conventional parametrization and the full potential local−density approximation+U calculations give a very similar band structure whose microscopic spectral character is consistent with the physical premise of the k⋅p kinetic-exchange model. On the other hand, the various models with a band structure comprising an...
We report on a systematic study of optical properties of (Ga,Mn)As epilayers spanning the wide range of accessible MnGa dopings. The material synthesis was optimized for each nominal Mn doping in order to obtain films which are as close as possible to uniform uncompensated (Ga,Mn)As mixed crystals. We observe a broad maximum in the mid-infrared absorption spectra whose position exhibits a prevailing blueshift for increasing Mn doping. In the visible range, a peak in the...
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