Theory of high-T_c superconductivity based on the fermion-condensation quantum phase transition

A theory of high temperature superconductivity based on the combination of the fermion-condensation quantum phase transition and the conventional theory of superconductivity is presented. This theory describes maximum values of the superconducting gap which can be as big as $\Delta_1\sim 0.1\epsilon_F$, with $\epsilon_F$ being the Fermi level. We show that the critical temperature $2T_c\simeq\Delta_1$. If there exists the pseudogap above $T_c$ then $2T^*\simeq\Delta_1$, and $T^*$ is the temperature at which the pseudogap vanishes. A discontinuity in the specific heat at $T_c$ is calculated. The transition from conventional superconductors to high-$T_c$ ones as a function of the doping level is investigated. The single-particle excitations and their lineshape are also considered.Comment: 6 pages, Revte

“Merciless Merciful Summer” by B. Melkevik: Collective Responsibility and Cancel Culture in Memorial Wars

This article describes the B. Melkevik’s philosophical and legal views on issues related to the legal understanding of collective memory, historical responsibility and collective guilt. The authors fit the researcher’s reasoning into the broad context of the development of ideas about collective responsibility and link the “ethical memory” criticized by B. Melkevik with the “cancel culture” and the spread of “new ethics”, suggesting the possibility of placing blame for the actions of one person on the group with which he identifies. The authors consider the limits of applicability of the concept of “Leta” B. Melkevik, believing that the conventional establishment of a regime of oblivion for historical memory through democratic procedures undermines the expertise of professional historical knowledge that provides a reliable Past. They come to the conclusion that the “cancel culture” characteristic of the digital media environment blocks the Habermas model of communicative rationality used by Melkevik

Media Memory in the Fanfiction Culture: the Image of Peter the Great in Online Literature

Поступила в редакцию: 15.03.2021. Принята к печати: 30.03.2021.Submitted: 15.03.2021. Accepted: 30.03.2021.Статья посвящается рассмотрению образа Петра I в сетевой литературе. Автор использует понятие «медиапамять» для описания феномена существования коллективных представлений о прошлом в медиа-среде. Культура фанфикшн рассматривается как одна из практик конструирования медиапамяти. Анализ художественных любительских текстов на краудсорсинговой платформе «Книга фанфиков» (ficbook.net) выявил способы выстраивания интернет-пользователями своего отношения к истории. Рассмотрение исторических текстов о Петровской эпохе показало, что пользовательские представления о Петре I крайне мифологизированы, основаны на стереотипах, которые преодолеваются свободной интерпретацией и актуализацией фактов прошлого при помощи образов современной массовой культуры.The article is devoted to the consideration of the image of Peter I in the online literature. The author uses the concept of media memory to describe the phenomenon of the existence of collective ideas about the past in the media environment. He considers the culture of fanfiction as one of the practices of constructing media memory. Analysis of amateur art texts on the crowdsourcing platform “Book of Fan Fiction” (ficbook.net) revealed the ways in which Internet users build their attitude to history. The review of historical texts about the Peter the Great era showed that the user’s ideas about Peter the Great are extremely mythologized, based on stereotypes that are overcome by the free interpretation and actualization of the facts of the past, with the help of images of modern mass culture.Исследование выполнено при финансовой поддержке РФФИ в рамках научного проекта № 20-09-42063 «Петр I в исторической памяти современной России: репрезентация образа в медиасреде»

Magnetoresistance of Highly Correlated Electron Liquid

The behavior in magnetic fields of a highly correlated electron liquid approaching the fermion condensation quantum phase transition from the disordered phase is considered. We show that at sufficiently high temperatures $T\geq T^*(x)$ the effective mass starts to depend on $T$, $M^*\propto T^{-1/2}$. This $T^{-1/2}$ dependence of the effective mass at elevated temperatures leads to the non-Fermi liquid behavior of the resistivity, $\rho(T)\propto T$ and at higher temperatures $\rho(T)\propto T^{3/2}$. The application of a magnetic field $B$ restores the common $T^2$ behavior of the resistivity. The effective mass depends on the magnetic field, $M^*(B)\propto B^{-2/3}$, being approximately independent of the temperature at $T\leq T^*(B)\propto B^{4/3}$. At $T\geq T^*(B)$, the $T^{-1/2}$ dependence of the effective mass is re-established. We demonstrate that this $B-T$ phase diagram has a strong impact on the magnetoresistance (MR) of the highly correlated electron liquid. The MR as a function of the temperature exhibits a transition from the negative values of MR at $T\to 0$ to the positive values at $T\propto B^{4/3}$. Thus, at $T\geq T^*(B)$, MR as a function of the temperature possesses a node at $T\propto B^{4/3}$.Comment: 7 pages, revtex, no figure

Soviet Leaders in Western Media Space

The results of the analysis of the USSR image in Western social media are presented. The novelty of the study lies in the use of the Global Database of Events, Language, and Tone in the analysis of the image of Soviet leaders in the Euro-Atlantic press. A review of messages that mention the names of the leaders of the USSR from January 1, 2017 to the present in the Western press has been completed. It is proved that the overall emotional tone of the narrative about the Soviet leaders in Western media is extremely negative. It is noted that French and German journalists, in comparison with Anglo-Saxon ones, more often write about Soviet history in a positive context. It is emphasized that the differences correlate with the quality of relations between Western countries and Russia, as well as the prospects for their improvement. It is shown that journalists, discussing the Soviet leaders, raise existential questions that are important for the Euro-Atlantic mass consciousness. The relevance of the study is due to the fact that the growth of media interest in the stories of rapprochement between the USSR and the West, as well as the emotionally positive transformation of the images of Soviet leaders in the media is considered as a condition and indicator of improving relations between Russia and the West

Ground state instability in systems of strongly interacting fermions

We analyze stability of a fermion system with model repulsive pair interaction potential. The possibility for different types of restructuring of the Fermi ground state (at sufficiently great coupling constant) is related to the analytic properties of such potential. In particular, for the screened Coulomb law it is shown that the restructuring cannot be of the Fermi condensation type, known earlier for some exactly solvable models, and instead it belongs to the class of topological transitions (TT). For this model, a phase diagram has been built in the variables "screening parameter - coupling constant" which displays two kinds of TT: a 5/2-kind similar to the known Lifshitz transitions in metals, and a 2-kind characteristic for a uniform strongly interacting system.Comment: The article has 11 pages, in Latex 2e (from Lyx), 3 eps figures or a ps fil

Flattening of Single-Particle Spectra in Strongly Correlated Electron Systems and the Violation of the Wiedemann-Franz Law

The renormalization of the Wiedemann-Franz (WF) ratio in strongly correlated electron systems is analyzed within the Landau quasiparticle picture. We demonstrate that the WF law is violated: (i) at the quantum critical point, where the effective mass diverges, and (ii) beyond a point of fermion condensation, where the single-particle spectrum $\epsilon(p)$ becomes flat. Results of the analysis are compared with available experimental data.Comment: 6 pages, 5 figures, added reference

Formation of conductive oxide scale on 33NK and 47Nd interconnector alloys for solid oxide fuel cells

Two grades of chromium-free alloys were studied in order to apply them as interconnectors for solid oxide fuel cells. The surface modification methods were proposed for each alloy with the purpose of forming of oxide scales considering the required physicochemical properties. Investigations of the structure and properties of the obtained oxide scales were performed and the efficiency of the chosen surface modification methods was approved. The samples with the surface modification exhibited higher conductivity values in comparison with the nonmodified samples. A compatibility study of samples with surface modification and glass sealant of chosen composition was accomplished. The modified samples demonstrated good adhesion during testing and electrical resistance less than 40 mOhm/cm2 at 850 ◦C in air, which allowed us to recommend these alloys with respective modified oxide scales as interconnectors for SOFC. © 2019 by the authors.Russian Foundation for Basic Research, RFBR: 17-58-10006This research was funded by the Russian Foundation of Basic Research grant number 17-58-10006. The facilities of the shared access center "Composition of Compounds" of IHTE UB RAS were used in this work

Spontaneous breaking of four-fold rotational symmetry in two-dimensional electronic systems explained as a continuous topological transition

The Fermi liquid approach is applied to the problem of spontaneous violation of the four-fold rotational point-group symmetry ($C_4$) in strongly correlated two-dimensional electronic systems on a square lattice. The symmetry breaking is traced to the existence of a topological phase transition. This continuous transition is triggered when the Fermi line, driven by the quasiparticle interactions, reaches the van Hove saddle points, where the group velocity vanishes and the density of states becomes singular. An unconventional Fermi liquid emerges beyond the implicated quantum critical point.Comment: 6 pages, 4 figure