Reconciling the interests of the economic diversification participants in a single-industry town

Рассматриваются проблемы согласования интересов участников процесса диверсификации экономики моногорода в процессе управления развитием моногорода на основе реализации стратегии диверсификации. Целью исследования является разработка инструментов гармонизации интересов участников процесса диверсификации экономики моногорода на основе разработки модели полного согласования интересов и сопоставления ее с моделью отдельно взятого моногорода. Методы исследования: системный подход, анализ и синтез, построение множеств согласования интересов с применением диаграммы Эйлера-Венна, методы комбинаторики, построение экономических показателей и рядов динамики, графический метод представления результатов и построения иерархии согласования интересов. Результаты исследования. Представлена модель полного согласования интересов различных групп лиц, в которой отражены сферы возможного пересечения интересов, а также иерархия числа согласуемых интересов. Предложены основные группы участников процесса диверсификации моногорода, а также разграничено понятие участника и роли (функции) участника в данном процессе. Обосновано и определено число множеств в зависимости от числа участников, чьи интересы одновременно согласуются, на примере моногорода Калтан Кемеровской области. На основе предложенной модели построена модель согласования интересов на примере моногорода Калтана. Полученная модель имеет трапециевидную форму, что свидетельствует о достаточно небольшом числе общих согласуемых интересов. Автор приходит к выводу, что в моногороде сформирован треугольник интересов «администрация города - малый бизнес в роли инвестора - вуз», представляющий основу в иерархии согласования интересов моногорода Калтан. Центральное положение при согласовании интересов с прочими участниками занимает исключительно администрация города. На основе данных выводов внесены предложения по направлениям дальнейшего согласования интересов на примере рассматриваемого моногорода.The article explores the problems of reconciling the interests of single-industry towns, a need that arises from the entire process of industry development management through a diversification strategy. The aim of this study is to develop tools to harmonize the interests of the single-industry towns, based on a model of full harmonization with the model of an individual single-industry town. Methods of the research: system approach, analysis and synthesis, building a set of harmonized interests with the application of the Eulerian-Venn diagram, combinatorics methods, construction of economic indicators and series of dynamics, graphical method of presentation of results and building the hierarchy of interests. Results of the study. The paper introduces the model for fully reconciling the interests of different groups of persons, reflecting the areas of possible intersecting interests and the hierarchy of the number of interests involved. The article proposes the main groups of participants in the diversification process and the differentially concept of participant and the role (function) of the participant in the diversification process. The author justifies and estimates the number of sets depending on the number of participants whose interests are concurrently reconciled in Kaltan case study. The proposed model is used for Kaltan, Kemerovo region case study. The result ing model is of a trapezoidal form, which indicates that there are quite a few common consenting interests. The author concludes that a triangle of interests «city administration - small business as investor - university» is formed. This triangle represents the highest level of harmonization of interests in the hierarchy. The city administration is in central position in reconciling interests with other participants. By the example of the considered single-industry town and based on these findings the suggestion on further harmonization of interests was made

Evidence for even parity unconventional superconductivity in Sr2RuO4

Funding: A.C. is grateful for support from the Julian Schwinger Foundation for Physics Research. A.P. acknowledges support by the Alexander von Humboldt Foundation through the Feodor Lynen Fellowship. Work at Los Alamos was funded by Laboratory Directed Research and Development (LDRD) program, and A.P. acknowledges partial support through the LDRD. N.K. acknowledges the support by the Grants-in-Aid for Scientific Research (KAKENHI, Grant JP18K04715 and JP21H01033) from Japan Society for the Promotion of Science (JSPS). The work at Dresden was funded by the Deutsche Forschungsgemeinschaft - TRR 288 - 422213477 (projects A10 and B01). The work at University of California, Los Angeles, was supported by NSF Grants 1709304 and 2004553.Unambiguous identification of the superconducting order parameter symmetry in Sr2RuO4 has remained elusive for more than a quarter century. While a chiral p-wave ground state analogue to superfluid 3He-A was ruled out only very recently, other proposed triplet-pairing scenarios are still viable. Establishing the condensate magnetic susceptibility reveals a sharp distinction between even-parity (singlet) and odd-parity (triplet) pairing since the superconducting condensate is magnetically polarizable only in the latter case. Here field-dependent 17O Knight shift measurements, being sensitive to the spin polarization, are compared to previously reported specific heat measurements for the purpose of distinguishing the condensate contribution from that due to quasiparticles. We conclude that the shift results can be accounted for entirely by the expected field-induced quasiparticle response. An upper bound for the condensate magnetic response of < 10% of the normal state susceptibility is sufficient to exclude all purely odd-parity candidates. PostprintPeer reviewe

Thermodynamic Evidence for a Two-Component Superconducting Order Parameter in Sr2_2RuO4_4

Sr$_2$RuO$_4$ has stood as the leading candidate for a spin-triplet superconductor for 26 years. Recent NMR experiments have cast doubt on this candidacy, however, and it is difficult to find a theory of superconductivity that is consistent with all experiments. What is needed are symmetry-based experiments that can rule out broad classes of possible superconducting order parameters. Here we use resonant ultrasound spectroscopy to measure the entire symmetry-resolved elastic tensor of Sr$_2$RuO$_4$ through the superconducting transition. We observe a thermodynamic discontinuity in the shear elastic modulus $c_{66}$, requiring that the superconducting order parameter is two-component. A two-component $p$-wave order parameter, such as $p_x+i p_y$, naturally satisfies this requirement. As this order parameter appears to be precluded by recent NMR experiments, we suggest that two other two-component order parameters, namely $\left\{d_{xz},d_{yz}\right\}$ or $\left\{d_{x^2-y^2},g_{xy(x^2-y^2)}\right\}$, are now the prime candidates for the order parameter of Sr$_2$RuO$_4$

High sensitivity heat capacity measurements on Sr2RuO4 under uniaxial pressure

Funding: Parts of this work were funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - TRR 288 -422213477 (projects A10 and B01). NK acknowledges the support from JSPS KAKENHI (nos. JP17H06136 and JP18K04715) and JST-Mirai Program (no. JPMJMI18A3) in Japan and YM from JSPS KAKENHI (nos. JP15H05852, JP15K21717) and JSPS core-to-core programme. YSL acknowledges the support of a St Leonard’s scholarship from the University of St Andrews, the Engineering and Physical Sciences Research Council via the Scottish Condensed Matter Centre for Doctoral Training under grant EP/G03673X/1, and the Max Planck Society.A key question regarding the unconventional superconductivity of Sr2RuO4 remains whether the order parameter is single- or two-component. Under a hypothesis of two-component superconductivity, uniaxial pressure is expected to lift their degeneracy, resulting in a split transition. The most direct and fundamental probe of a split transition is heat capacity. Here, we report development of new high-frequency methodology for measurement of heat capacity of samples subject to large and highly homogeneous uniaxial pressure. We place an upper limit on the heat capacity signature of any second transition of a few per cent of the primary superconducting transition. The normalized jump in heat capacity, Δ C/C, grows smoothly as a function of uniaxial pressure, but we find no qualitative evidence of a pressure-induced order parameter transition. Thanks to the high precision of our measurements, these findings place stringent constraints on theories of the superconductivity of Sr2RuO4.PostprintPeer reviewe

Strong peak in Tc of Sr2RuO4 under uniaxial pressure

Sr2RuO4 is an unconventional superconductor that has attracted widespread study because of its high purity and the possibility that its superconducting order parameter has odd parity. We study the dependence of its superconductivity on anisotropic strain. Applying uniaxial pressures of up to ~1 gigapascals along a 〈100〉 direction (a axis) of the crystal lattice results in the transition temperature (Tc) increasing from 1.5 kelvin in the unstrained material to 3.4 kelvin at compression by ≈0.6%, and then falling steeply. Calculations give evidence that the observed maximum Tc occurs at or near a Lifshitz transition when the Fermi level passes through a Van Hove singularity, and open the possibility that the highly strained, Tc = 3.4 K Sr2RuO4 has an even-parity, rather than an odd-parity, order parameter.PostprintPeer reviewe

Elastocaloric determination of the phase diagram of Sr2_2RuO4_4

One of the main developments in unconventional superconductivity in the past two decades has been the discovery that most unconventional superconductors form phase diagrams that also contain other strongly correlated states. Many systems of interest are therefore close to more than one instability, and tuning between the resultant ordered phases is the subject of intense research1. In recent years, uniaxial pressure applied using piezoelectric-based devices has been shown to be a particularly versatile new method of tuning, leading to experiments that have advanced our understanding of the fascinating unconventional superconductor Sr$_2$RuO$_4$. Here we map out its phase diagram using high-precision measurements of the elastocaloric effect in what we believe to be the first such study including both the normal and the superconducting states. We observe a strong entropy quench on entering the superconducting state, in excellent agreement with a model calculation for pairing at the Van Hove point, and obtain a quantitative estimate of the entropy change associated with entry to a magnetic state that is observed in proximity to the superconductivity. The phase diagram is intriguing both for its similarity to those seen in other families of unconventional superconductors and for extra features unique, so far, to Sr$_2$RuO$_4$

Upper Critical Field of Sr2_2RuO4_4 under In-Plane Uniaxial Pressure

In-plane uniaxial pressure has been shown to strongly tune the superconducting state of Sr$_2$RuO$_4$ by approaching a Lifshitz transition and associated Van Hove singularity (VHS) in the density of states. At the VHS, $T_c$ and the in- and out-of-plane upper critical fields are all strongly enhanced, and the latter has changed its curvature as a function of temperature from convex to concave. However, due to strain inhomogeneity it has not been possible so far to determine how the upper critical fields change with strain. Here, we show the strain dependence of both upper critical fields, which was achieved due to an improved sample preparation. We find that the in-plane upper critical field is mostly linear in $T_c$. On the other hand, the out-of-plane upper critical field varies with a higher power in $T_c$, and peaks strongly at the VHS. The strong increase in magnitude and the change in form of $H_\mathrm{c2||c}$ occur very close to the Van Hove strain, and points to a strong enhancement of both the density of states and the gap magnitude at the Lifshitz transition

Kazalo

The superconducting state in the quasi-two-dimensional and strongly correlated Sr$_2$RuO$_4$ is uniquely held up as a solid state analog to superfluid $^3$He-$A$, with an odd-parity order parameter that also breaks time reversal symmetry, and for which the vector order parameter has the same direction in spin space for all electron momenta. The recent discovery that uniaxial pressure causes a steep rise and maximum in transition temperature ($T_c$) in strained samples motivated the study of $^{17}$O nuclear magnetic resonance (NMR) that we describe in this article. A reduction of Knight shifts $K$ was observed for all strain values and temperatures $T<T_c$, consistent with a drop in spin polarization in the superconducting state. In unstrained samples, our results are in contradiction with a body of previous NMR work, and with the most prominent previous proposals for the order parameter of Sr$_2$RuO$_4$. Possible alternative scenarios are discussed.Comment: Manuscript: 4 figures, 2 tables; Supplementary Information: 5 figure

Normal state 17O NMR studies of Sr2RuO4 under uniaxial stress

This work was supported in part by the Laboratory Directed Research and Development (LDRD) program of Los Alamos National Laboratory under Project No. 20170204ER. Y. L. acknowledges partial support through the LDRD and 1000 Youth Talents Plan of China. N. K. acknowledges the support from JSPS KAKNHI (Grant No. 18K04715). I. I.M. is supported by ONR through the NRL basic research program. This work is supported in part by the National Science Foundation (Grants No. DMR-1410343 and No. DMR-1709304).The effects of uniaxial compressive stress on the normal state 17O nuclear-magnetic-resonance properties of the unconventional superconductor Sr2RuO4 are reported. The paramagnetic shifts of both planar and apical oxygen sites show pronounced anomalies near the nominal a-axis strain ϵaa≡ϵv that maximizes the superconducting transition temperature Tc. The spin susceptibility weakly increases on lowering the temperature below T≃10  K, consistent with an enhanced density of states associated with passing the Fermi energy through a van Hove singularity. Although such a Lifshitz transition occurs in the γ band formed by the Ru dxy states hybridized with in-plane O pπ orbitals, the large Hund’s coupling renormalizes the uniform spin susceptibility, which, in turn, affects the hyperfine fields of all nuclei. We estimate this “Stoner” renormalization S by combining the data with first-principles calculations and conclude that this is an important part of the strain effect, with implications for superconductivity.Publisher PDFPeer reviewe