Information Theory in Describing the Electronic Structures of Atoms

An information approach to the description of atoms by introducing »differential« entropy characteristics of chemical elements has been developed. These quantities clearly reflect the horizontal and vertical structure of the periodic table, and the main features of atomic electron structures, such as delay in filling d- and f-subshells, the action of Hund\u27s first rule, the anomalies in the electronic structure of some atoms, the appearance of the first electron having a given value of some quantum number, etc. The necessity of change in the position of lanthanides and actinides in the periodic table is discussed

Anomalous Normal-State Properties of High-Tc_c Superconductors -- Intrinsic Properties of Strongly Correlated Electron Systems?

A systematic study of optical and transport properties of the Hubbard model, based on Metzner and Vollhardt's dynamical mean-field approximation, is reviewed. This model shows interesting anomalous properties that are, in our opinion, ubiquitous to single-band strongly correlated systems (for all spatial dimensions greater than one), and also compare qualitatively with many anomalous transport features of the high-T$_c$ cuprates. This anomalous behavior of the normal-state properties is traced to a ``collective single-band Kondo effect,'' in which a quasiparticle resonance forms at the Fermi level as the temperature is lowered, ultimately yielding a strongly renormalized Fermi liquid at zero temperature.Comment: 27 pages, latex, 13 figures, Invited for publication in Advances in Physic

AV3_3Sb5_5 Kagome Superconductors: Progress and Future Directions

The recent discovery of the AV$_3$Sb$_5$ (A=K, Rb, Cs) kagome superconductors launched a growing field of research investigating electronic instabilities in kagome metals. Specifically, the AV$_3$Sb$_5$ family naturally exhibits a Fermi level tuned to the Van Hove singularities associated with the saddle points formed from the prototypical kagome band structure. The charge density wave and superconducting states that form within the kagome networks of these compounds exhibit a number of anomalous properties reminiscent of theoretical predictions of exotic states in kagome metals tuned close to their Van Hove fillings. Here we provide an overview of the key structural and electronic features of AV$_3$Sb$_5$ compounds and review the status of investigations into their unconventional electronic phase transitions.Comment: 6 figures, 17 page

Fosfogenees ja haruldaste muldmetallide diagenees tänapäevastes ja Paleosoilistes fosforiitides

Väitekirja elektrooniline versioon ei sisalda publikatsiooneFosfor on elusloodusele kandva tähtsusega keemiline element ning ühtlasi primaarproduktsiooni kontrolliv toitaine. Fosfori settese sidumise mehhanism ehk fosfogenees on siiani paljuski ebaselge. Peamine fosforit sisaldav mineraal setetes on apatiit, mille kristallstruktuuri on võimalik asenduda suurel hulgal erinevatel keemilistel elementidel. Üks olulisemaid asenduvaid elementide rühmasi on haruldased muldmetallid ja üttrium ehk REE+Y. Käesolevas doktoritöös uuriti <5 miljoni aasta vanuseid fosforiite Namiibia šelfil ning ~ 490 miljoni aasta vanuseid Eesti biogeenseid fosforiite. Töö peamisteks eesmärkideks oli selgitada fosfogeneesiks vajalikud keskkonnatingimused ning haruldaste muldmetallide sidustamise ja ümberjaotumine mehhanismid. Töö fookuses olid REE+Y süstemaatika fosforiitides nii lühiajalisel kui pikaajalisel skaalal, stabiilsete isotoopide ja jälgelementide käitumine apatiidi väljasettimise ajal ning väljasettinud apatiidi mikromorfoloogia. Käesoleva töö tulemused näitavad, et fosfogeneesi levikut kontrollivad hapnikurikaste ja –vaesete tingimuste varieerumine settes ning apatiidi settimiseks vaja minevate orgaaniliste substraatide olemasolu. REE+Y sidustamine apatiiti toimub geoloogilisel ajaskaalal kiiresti ning ka väga noortel fosforiitidel on jälgelementide koostis oluliselt erinev algupärasest. Peamiseks REE+Y allikaks apatiidis on hapnikuvaene poorivesi. Apatiidi settimise ajal poorivee valdav keemiline koostis kontrollib REE+Y sidustamist ja seeläbi nende elementide sisaldust fosforiidis. Sellest tulenevalt võivad üksteisest paarikümne kilomeetri kaugusel paiknevate fosforiidi leiukohtade REE+Y kontsentratsioonid varieeruda enam kui kümme korda.Phosphorus is an essential element for all life on Earth as well as the key limiting nutrient on geological timescales. However, the formation of solid phosphate phases – phosphogenesis – is poorly constrained. The main phosphate containing mineral in marine sediments is apatite. Due to its complex crystal structure, apatite is susceptible to a wide variety of substitutions. One of the most important chemical substitutions in apatite are a group of 15 elements called Rare Earth Elements and Yttrium (REE+Y). In this thesis, Recent Namibian sedimentary phosphorites and ~490 mln year old Estonian phosphorites were studied. The main goal of this doctoral thesis was to decipher the environmental conditions during phosphogenesis and the diagenetic evolution of sedimentary phosphorites. The specific aims of this thesis were to study the stable isotopic and trace element systematics in Recent sedimentary apatites and the post-depositional short- and long-term changes in apatite REE+Y composition. The thesis concludes that dominantly suboxic conditions punctuated by short-term sulfidic conditions, coupled with organic matter derived nucleation surfaces control both the depth and spatial distribution of phosphogenesis. Uptake of REE+Y by apatite is a fast-paced process on geological timescales and primary REE+Y signatures are already altered in Recent phosphorites. The dominant source for REE+Y in apatite is suboxic-sulfidic pore-water. The chemical environment of pore-water immediately after deposition of apatite controls the degree of enrichment of REE+Y in phosphorites, and can result in up to 10-fold REE+Y abundance variability between phosphorite localities a few tens of kilometres apart.https://www.ester.ee/record=b546561

A Real Space Description of Magnetic Field Induced Melting in the Charge Ordered Manganites: I. The Clean Limit

We study the melting of charge order in the half doped manganites using a model that incorporates double exchange, antiferromagnetic superexchange, and Jahn-Teller coupling between electrons and phonons. We primarily use a real space Monte Carlo technique to study the phase diagram in terms of applied field $(h)$ and temperature $(T)$, exploring the melting of charge order with increasing $h$ and its recovery on decreasing $h$. We observe hysteresis in this response, and discover that the `field melted' high conductance state can be spatially inhomogeneous even without extrinsic disorder. The hysteretic response plays out in the background of field driven equilibrium phase separation. Our results, exploring $h$, $T$, and the electronic parameter space, are backed up by analysis of simpler limiting cases and a Landau framework for the field response. This paper focuses on our results in the `clean' systems, a companion paper studies the effect of cation disorder on the melting phenomena.Comment: 16 pages, pdflatex, 11 png fig

Vortices in quantum droplets: Analogies between boson and fermion systems

The main theme of this review is the many-body physics of vortices in quantum droplets of bosons or fermions, in the limit of small particle numbers. Systems of interest include cold atoms in traps as well as electrons confined in quantum dots. When set to rotate, these in principle very different quantum systems show remarkable analogies. The topics reviewed include the structure of the finite rotating many-body state, universality of vortex formation and localization of vortices in both bosonic and fermionic systems, and the emergence of particle-vortex composites in the quantum Hall regime. An overview of the computational many-body techniques sets focus on the configuration interaction and density-functional methods. Studies of quantum droplets with one or several particle components, where vortices as well as coreless vortices may occur, are reviewed, and theoretical as well as experimental challenges are discussed.Comment: Review article, 53 pages, 53 figure

The tetrad effect and geochemistry of apatite from the Altay Koktokay No. 3 pegmatite, Xinjiang, China: implications for pegmatite petrogenesis

In order to better constrain the evolution and petrogenesis of pegmatite, geochemical analysis was conducted on a suite of apatite crystals from the Altay Koktokay No. 3 pegmatite, Xinjiang, China and from the granitic and amphibolitic wall rocks. Apatite samples derived from pegmatite zones show convex tetrad effects in their REE patterns, extremely negative Eu anomalies and non-chondritic Y/Ho ratios. In contrast, chondritic Y/Ho ratios and convex tetrad effects are observed in the muscovite granite suggesting that different processes caused non-chondritic Y/Ho ratios and lanthanide tetrad effects. Based on the occurrence of convex tetrad effects in the host rocks and their associated minerals, we propose that the tetrad effects are likely produced from immiscible fluoride and silicate melts. This is in contrast to previous explanations of the tetrad effect; i.e. surface weathering, fractional crystallization and/or fluid-rock interaction. Additionally, we put forward that extreme negative Eu and non-chondritic Y/Ho in apatite are likely caused by the large amount of hydrothermal fluid exsolved from the pegmatite melts. Evolution of melt composition was found to be the primary cause of inter and intra-crystal major and trace element variations in apatite. Mn entering into apatite via substitution of Ca is supported by the positive correlation between CaO and MnO. Different evolution trends in apatite composition imply different crystallization environments between wall rocks and pegmatite zones. Based on the geochemistry of apatite samples, it is likely that there is a genetic relationship between the source of muscovite granite and the source of the pegmatite

Experimental Studies of Electrical Resistivity Behavior of Cu, Zn and Co Along Their Melting Boundaries: Implications for Heat Flux at Earth’s Inner Core Boundary

Abstract The electrical resistivity of high purity Cu, Zn and Co has been measured at pressures (P) up to 5GPa and at temperatures (T) in the liquid phase. The electrical resistivity of solid state Nb was also measured up to 5GPa and ~1900K. All measurements were made in a large volume cubic anvil press. Using two thermocouples placed at opposite ends of the sample wire, serving as temperature probes as well as resistance leads, a four-wire technique resistivity measurement was employed along with a polarity switch. Post-experiment compositional analyses were carried out on an electron microprobe. The expected resistivity decrease with P and increase with T were found in all metals in the solid state and comparisons with 1atm data are in very good agreement. The melting temperature data were obtained from the large resistivity jumps at the solid-liquid transition and these agree with other experimental studies. The main results of this work are that resistivity of Cu decreases along its P,T-dependent melting boundary, while the resistivity of Zn and Co remain constant along their P,T-dependent melting boundaries. These findings are interpreted in terms of the competing effects of P and T on the electronic structure of filled and unfilled d-band liquid transition metals. For Nb, an electronic transition was observed in the T-dependence of electrical resistivity at high P, T. The transition is discussed in terms of the effects of P and T on the electronic band structure of Nb causing a change in resistivity from behavior characterizing the ‘minus group’ to the ‘plus group’. The electronic thermal conductivity is calculated from resistivity data using the Wiedemann-Franz law and is shown to increase with P in both the solid and liquid states for Cu, Zn and Co but upon T increase, it decreases in the solid and increases in the liquid state. For Nb, above the transition T, the T-dependence of electronic thermal conductivity of Nb remains constant at 2GPa and exhibits an increasingly negative slope at higher P. The electronic thermal conductivity of Nb increased with increasing pressure at any given isotherm. The implications for heat flow and thermal evolution in Earth’s and other terrestrial planetary cores are based on the similarity of electronic structure of Co and Fe. The invariance of resistivity along the melting boundary of Co suggests thermal conductivity at the inner core boundary of an Fe dominated core may be similar to the value of Fe at its 1 atm melting temperature