Order Fluctuations Research Articles

Absence of Superconductivity in the Hubbard Dimer Model for κ-(BEDT-TTF)2X

In the most studied family of organic superconductors κ-(BEDT-TTF)2X, the BEDT-TTF molecules that make up the conducting planes are coupled as dimers. For some anions X, an antiferromagnetic insulator is found at low temperatures adjacent to superconductivity. With an average of one hole carrier per dimer, the BEDT-TTF band is effectively 12-filled. Numerous theories have suggested that fluctuations of the magnetic order can drive superconducting pairing in these models, even as direct calculations of superconducting pairing in monomer 12-filled band models find no superconductivity. Here, we present accurate zero-temperature Density Matrix Renormalization Group (DMRG) calculations of a dimerized lattice with one hole per dimer. While we do find an antiferromagnetic state in our results, we find no evidence for superconducting pairing. This further demonstrates that magnetic fluctuations in the effective 12-filled band approach do not drive superconductivity in these and related materials.

ANALISIS PENGARUH TINGKAT SUKU BUNGA, NILAI TUKAR DAN INFLASI TERHADAP HARGA SAHAM PERBANKAN PADA TAHUN 2011-2020

The purpose of this study is to reaffirm the effect of interest rates, exchange rates and inflation on banking stock prices in 2011-2020 and to strengthen the results of previous studies. The data sources for this research were obtained from the official website of Bank Indonesia, the Central Bureau of Statistics, and the Indonesia Stock Exchange. The population in this study were 45 banks. The research sample used was purposive sampling technique. The analysis technique used is a quantitative technique, then it is estimated by means of a qualitative test of the influence of the variables both simultaneously and partially and using a panel data regression model test, classical assumptions, linear data panel analysis to the coefficient of determination r-square. The results showed that the results of the separate test showed a positive and significant effect on the interest rate variable, then the exchange rate variable obtained a positive and significant effect while the inflation variable had a negative and insignificant effect. This is because if inflation occurs, the price will decrease so that inflation must continue to increase and in such a way that there are no fluctuations in order to stabilize inflation.

An investigation of reentrant spin-glass behavior, magnetocaloric effect and critical behavior of MnCr2O4

The spin-glass (SG) behavior, magnetocaloric effect, and critical behavior of MnCr2O4 were investigated using dc/ac magnetic measurements. The strong magnetic anisotropy is observed from the dc magnetizations. The peaks of ac susceptibility display dependence on the frequency and magnetic field. Meanwhile, magnetic relaxation measurements show a slow decay of the remanent magnetization with time. These findings consistently demonstrate the coexistence of the SG component and long-range ferrimagnetic (FIM) order in MnCr2O4. The SG at low temperature is not conventional but has a reentrant character. Importantly, the reentrant SG (RSG) behavior in MnCr2O4 originates from the freezing and fluctuation of the short-range spiral order at low temperatures. On the other hand, the magnetocaloric effect (MCE) in spinel compounds MnCr2O4 was reported in this study. According to the isotherms measurements, the magnetic entropy change |ΔSM|=6.1 J kg−1 K−1 was calculated under applied field H = 50 kOe. A comprehensive study of the critical behavior of MnCr2O4 near the paramagnetic (PM) to FIM transition, might be helpful in understanding the interesting magnetic interaction of MnCr2O4. Besides, the critical exponents of MnCr2O4 was obtained [β = 0.488 and γ = 0.918 for MAP, β = 0.473 and γ = 0.909 for KF] by the different theoretical models. Interestingly, it is found that the critical phenomena of MnCr2O4 are close to the mean-field model.

Search antecedents and outcomes of new venture perceived and actual knowledge incongruence

This study explores the new venture knowledge search process, including what role differences in perceived and actual knowledge play, and the resulting influence on strategic choice and performance. A model was created that identifies proposed relationships among key constructs associated with knowledge satisfaction, search, strategy, and new venture performance. We found that perceived relative knowledge strength is deemed to influence the degree of strategic leverage a new venture selects, which subsequently influences performance, contingent on actual relative knowledge strength. The model more clearly distinguishes the role of search in perceived and actual knowledge, which identifies potentially disadvantageous effects on strategic choice and performance. Research implications include the importance of acknowledging that perceived knowledge is just as critical as actual knowledge when utilizing the resource‐based and knowledge‐based views of the firm. Both internal and external search contain advantages and disadvantages that are important for firms trying to achieve external fit within a dynamic competitive environment. Practical implications include that new ventures should be cognizant of potential differences between perceived knowledge and actual knowledge because any incongruence can mislead new ventures in their search efforts and strategic initiatives. Moreover, new ventures should continually engage in external search, even when they have superior knowledge, because the process of external search provides a variety of competitive information that can help new ventures determine their degree of advantage. New ventures also need to recognize the dynamic nature of competition and accurately assess performance fluctuations in order to enhance their performance.

Discrepant responses between evapotranspiration- and transpiration-based ecosystem water use efficiency to interannual precipitation fluctuations

Climate change intensifies precipitation fluctuation and increases drought frequency around the globe. Water use efficiency (WUE) has proven to be a crucial metric to quantify the trade-off linking global carbon and water cycles in many aspects of terrestrial ecosystem function. Investigating the response of ecosystem WUE to multiannual precipitation fluctuations has major implications for our understanding of ecosystem carbon and water dynamics. However, the impacts of water availability variation on evapotranspiration- and transpiration-based ecosystem WUE and their mechanisms are poorly understood due to limited observations. We investigated ecosystem WUE in response to interannual precipitation fluctuations in order to reveal the regularity underlying WUE changes under different levels of water stress. We optimized the parameters of two remote sensing models (PT-JPL and PM) based on different biophysical processes using the differential-evolution Markov Chain (DE-MC) method. We investigated ecosystem WUEET (GPP/ET) and WUET (GPP/T) in response to interannual precipitation fluctuations at 73 sites. We found ecosystem WUET appears to decline during drought years and to increase in wet years contrasting with WUEET, which was mostly attributable to differing sensitivities of GPP, ET and T to multiannual precipitation fluctuations. The vegetation generally consumes more T to improve ecosystem GPP during dry years, meanwhile, no apparent change in WUEET during dry years because of the trade of between GPP/T and T/ET. The replenishment of soil moisture to ecosystem transpiration is higher than we thought during dry years. This was masked in analysis that considered the responses of GPP and T to annual precipitation changes separately, but was revealed by the changes in ecosystem WUET. This research advances our understanding of the consequences of water fluctuation on ecosystem carbon and water exchange.

Effects of hadronic repulsive interactions on the fluctuations of conserved charges

We investigate the effects of repulsive interaction between hadrons on the fluctuations of the conserved charges. We calculate the baryon,the electric charge and the strangeness susceptibilities within the ambit of hadron resonance gas model extended to include the short range repulsive interactions.The repulsive interactions are included through a mean-field approach where the single particle energy gets modified due to mean field interactions between hadrons proportional to the number density of hadrons.We assume different mean-field interactions for mesons and baryons. It is shown that the repulsive interactions play a very crucial role to describe hadronic matter near transition temperature. We also show that in order to consistently describe higher order conserved charge fluctuations mesonic repulsive interactions cannot be neglected. Further, we demonstrate that the repulsive interaction of baryons are essential to describe the lattice simulation results at finite baryonchemical potential for higher order fluctuations.

Superfluid quantum criticality in liquid He3 in anisotropic aerogel

In the novel superfluid polar phase realized in liquid 3He in highly anisotropic aerogels, a quantum transition to the polar-distorted A (PdA) phase may occur at a low but finite pressure Pc(0). It is shown that a nontrivial quantum dynamics of the critical fluctuation of the PdA order is induced by the presence of both the columnar-like impurity scattering leading to the Anderson's Theorem for the polar phase and the line node of the quasiparticle gap in the state, and that, in contrast to the situation of the normal to the B phase transition in isotropic aerogels, a weakly divergent behavior of the compressibility appears in the quantum critical region close to Pc(0).

First passage time in post-transcriptional regulation by multiple small RNAs.

The post-transcriptional regulation of a protein by multiple small RNA molecules has been formulated as a stochastic process. An approximate solution of the master equation shows that the protein statistics can exhibit a generic form applicable for many regulatory scenarios. The first passage time (FPT) statistics has been obtained for regulation by single sRNA, with negative and positive regulations as limiting cases, as well as regulation by multiple sRNAs. The multiple sRNAs are able to independently control protein mean and variance, and we show that this is an advantageous mechanism to control FPT fluctuations in order to improve timing efficiency in post-transcriptional regulation.

High-pressure phase diagrams of FeSe1\u2212xTex: correlation between suppressed nematicity and enhanced superconductivity

The interplay among magnetism, electronic nematicity, and superconductivity is the key issue in strongly correlated materials including iron-based, cuprate, and heavy-fermion superconductors. Magnetic fluctuations have been widely discussed as a pairing mechanism of unconventional superconductivity, but recent theory predicts that quantum fluctuations of nematic order may also promote high-temperature superconductivity. This has been studied in FeSe1−xSx superconductors exhibiting nonmagnetic nematic and pressure-induced antiferromagnetic orders, but its abrupt suppression of superconductivity at the nematic end point leaves the nematic-fluctuation driven superconductivity unconfirmed. Here we report on systematic studies of high-pressure phase diagrams up to 8 GPa in high-quality single crystals of FeSe1−xTex. When Te composition x(Te) becomes larger than 0.1, the high-pressure magnetic order disappears, whereas the pressure-induced superconducting dome near the nematic end point is continuously found up to x(Te) ≈ 0.5. In contrast to FeSe1−xSx, enhanced superconductivity in FeSe1−xTex does not correlate with magnetism but with the suppression of nematicity, highlighting the paramount role of nonmagnetic nematic fluctuations for high-temperature superconductivity in this system.

Tuning the 1H NMR Paramagnetic Relaxation Enhancement and Local Order of [Aliquat]+-Based Systems Mixed with DMSO.

Understanding the behavior of a chemical compound at a molecular level is fundamental, not only to explain its macroscopic properties, but also to enable the control and optimization of these properties. The present work aims to characterize a set of systems based on the ionic liquids [Aliquat][Cl] and [Aliquat][FeCl] and on mixtures of these with different concentrations of DMSO by means of H NMR relaxometry, diffusometry and X-ray diffractometry. Without DMSO, the compounds reveal locally ordered domains, which are large enough to induce order fluctuation as a significant relaxation pathway, and present paramagnetic relaxation enhancement for the [Aliquat][Cl] and [Aliquat][FeCl] mixture. The addition of DMSO provides a way of tuning both the local order of these systems and the relaxation enhancement produced by the tetrachloroferrate anion. Very small DMSO volume concentrations (at least up to 1%) lead to enhanced paramagnetic relaxation without compromising the locally ordered domains. Larger DMSO concentrations gradually destroy these domains and reduce the effect of paramagnetic relaxation, while solvating the ions present in the mixtures. The paramagnetic relaxation was explained as a correlated combination of inner and outer-sphere mechanisms, in line with the size and structure differences between cation and anion. This study presents a robust method of characterizing paramagnetic ionic systems and obtaining a consistent analysis for a large set of samples having different co-solvent concentrations.

Nematic fluctuations in iron-oxychalcogenide Mott insulators

Nematic fluctuations occur in a wide range physical systems from biological molecules to cuprates and iron pnictide high-Tc superconductors. It is unclear whether nematicity in pnictides arises from electronic spin or orbital degrees of freedom. We studied the iron-based Mott insulators La2O2Fe2OM2M = (S, Se), which are structurally similar to pnictides. Nuclear magnetic resonance revealed a critical slowing down of nematic fluctuations and complementary Mössbauerr spectroscopy data showed a change of electrical field gradient. The neutron pair distribution function technique detected local C2 fluctuations while neutron diffraction indicates that global C4 symmetry is preserved. A geometrically frustrated Heisenberg model with biquadratic and single-ion anisotropic terms provides the interpretation of the low temperature magnetic fluctuations. The nematicity is not due to spontaneous orbital order, instead it is linked to geometrically frustrated magnetism based on orbital selectivity. This study highlights the interplay between orbital order and spin fluctuations in nematicity.

ISM and fuzzy logic approach to model and analyze the variables in downstream supply chain for perfect order fulfillment

PurposeAs we move up in the supply chain (SC) from retailer to supplier, amplification in the fluctuation of order increased. To minimize this amplification, understanding of key decision variables which affects the SC is essential. So, in the present work the authors developed a novel approach to examine the structural dependencies among variables responsible for perfect order fulfillment (POF).Design/methodology/approachInterpretive structural modeling approach has been used to model the structural relationship among the key SC variables. Further, to study the driver-dependence dynamics among variables MICMAC analysis has been used. In the second phase, the influence of driver variables on the POF is investigated by using fuzzy logic.FindingsFrom the results, it is observed that the variables’ delivery time, number of echelons, data accuracy and information sharing have high driving power which may help the organizations to meet challenges offered by POF. The results showed that for POF is said to be at optimum level when the number of echelons should be low and data accuracy should be high, and information sharing among all partners should also be very high.Research limitations/implicationsResearch on SC is classified into three categories, i.e. operational, design and strategic. In the present study authors discussed strategic variables responsible for POF which is the main limitation of the study. The work can be extended by including operational and design variables.Practical implicationsPOF in SC network is affected by various variables. The in-depth understanding of contextual association among the variables helps the managers to improve the efficiency of the SC and reduce the bullwhip effect across the downstream SC network.Originality/valueThe study presents a hybrid approach to analyze the key POF dimensions, i.e. forecasting, number of echelons, information sharing, cycle time and delivery time, critical to POF in downstream SC network by developing various case settings.

The Mysteries of Charge Order and Charge Fluctuations in Cuprate Superconductors

This Special Topics issue condenses the latest research on the enigmatic characteristics of high-temperature superconductivity in cuprates through the observation and elucidation of charge order, charge fluctuations, and other phenomena.

Higher order fluctuation fields and orthogonal duality polynomials

Inspired by the works in [2] and [11] we introduce what we call k-th-order fluctuation fields and study their scaling limits. This construction is done in the context of particle systems with the property of orthogonal self-duality. This type of duality provides us with a setting in which we are able to interpret these fields as some type of discrete analogue of powers of the well-known density fluctuation field. We show that the weak limit of the k-th order field satisfies a recursive martingale problem that corresponds to the SPDE associated with the kth-power of a generalized Ornstein-Uhlenbeck process.

Chemical freeze-out parameters of net-kaons in heavy-ion collisions

We study chemical freeze-out parameters for heavy-ion collisions by performing two different thermal analyses. We analyze results from thermal fits for particle yields, as well as, net-charge fluctuations in order to characterize the chemical freeze-out. The Hadron Resonance Gas (HRG) model is employed for both methods. By separating the light hadrons from the strange hadrons in thermal fits, we study the proposed flavor hierarchy. For the net-charge fluctuations, we calculate the mean-over-variance ratio of the net-kaon fluctuations in the HRG model at the five highest energies of the RHIC Beam Energy Scan (BES) for different particle data lists. We compare these results with recent experimental data from the STAR collaboration in order to extract sets of chemical freeze-out parameters for each list. We focused on particle lists which differ largely in the number of resonant states. By doing so, our analysis determines the effect of the amount of resonances included in the HRG model on the freeze-out conditions. Our findings have potential impact on various other models in the field of relativistic heavy ion collisions.

Tan's contact as an indicator of completeness and self-consistency of a theory

It is well known that, Tan's contact could be calculated by using any of following three methods: by the asymptotic behavior of momentum distribution; by Tan's adiabatic sweep theorem; or by the operator product expansion as an expectation value of the interaction term. We argue that, if a theory describing Bose (or Fermi) system with the only contact interaction is self consistent, then it should lead to the same result in all three cases. As an example we considered MFT based approaches and established that among existing approximations of MFT, the Hartree - Fock - Bogoliubov (HFB) approach is the most self consistent. Actually, HFB is able to describe existing experimental data on Tan's contact for dilute Bose gas, but fails to predict its expected behavior at large gas parameter $(\gamma > 0.015)$. So, for appropriate description of properties of a Bose gas even at zero temperature, this approximation needs to be expanded by taking into account fluctuations in higher order then the second one.

Porosity distribution in cyclic dolomites of the Lower Qiulitag Group (Upper Cambrian) in northwestern Tarim Basin, China

ABSTRACT Increasing interests in hydrocarbon resources at depths have drawn greater attentions to the deeply-buried carbonate reservoirs in the Tarim Basin in China. In this study, the cyclic dolomite rocks of Upper Cambrian Lower Qiulitag Group from four outcrop sections in northwestern Tarim Basin were selected to investigate and evaluate the petrophysical properties in relation to depositional facies and cyclicity. The Lower Qiulitag Group includes ten lithofacies, which were deposited in intermediate to shallow subtidal, restricted shallow subtidal, intertidal, and supratidal environments on a carbonate ramp system. These lithofacies are vertically stacked into repeated shallowing-upward, meter-scale cycles which are further grouped into six third-order depositional sequences (Sq1 to Sq6). There are variable types of pore spaces in the Lower Qiulitag Group dolomite rocks, including interparticle, intraparticle, and fenestral pores of primary origin, inter crystal, and vuggy pores of late diagenetic modification. The porosity in the dolomites is generally facies-selective as that the microbially-originated thrombolites and stromatolites generally yield a relatively high porosity. In contrast, the high-energy ooidal grainstones generally have very low porosity. In this case, the microbialite-based peritidal cycles and peritidal cycle-dominated highstand (or regressive) successions have relatively high volumes of pore spaces, although highly fluctuating (or vertical inhomogeneous). Accordingly, the grainstone-based subtidal cycles and subtidal cycle-dominated transgressive successions generally yield extremely low porosity. This scenario indicates that porosity development and preservation in the thick dolomite successions are primarily controlled by depositional facies which were influenced by sea-level fluctuations of different orders and later diagenetic overprinting.

Effect of controlled pointlike disorder induced by 2.5-MeV electron irradiation on the nematic resistivity anisotropy of hole-doped (Ba,K)Fe2As2

In-plane anisotropy of electrical resistivity was studied in samples of the hole-doped Ba$_{1-x}$K$_x$Fe$_2$As$_2$ in the composition range $0.21 \leq x \leq 0.26$ where anisotropy changes sign. Low-temperature ($\sim$20~K) irradiation with relativistic 2.5 MeV electrons was used to control the level of disorder and residual resistivity of the samples. Modification of the stress-detwinning technique enabled measurements of the same samples before and after irradiation, leading to conclusion of anisotropic character of predominantly inelastic scattering processes. Our main finding is that the resistivity anisotropy is of the same sign irrespective of residual resistivity, and remains the same in the orthorhombic $C_2$ phase above the re-entrant tetragonal transition. Unusual $T$-linear dependence of the anisotropy $\Delta \rho \equiv \rho_a(T)-\rho_b(T)$ is found in pristine samples with $x=$0.213 and $x=$0.219, without similar signatures in either $\rho_a(T)$ or $\rho_b(T)$. We show that this feature can be reproduced by a phenomenological model of R.~M.~Fernandes {\it et al.} Phys. Rev. Lett. {\bf 107},217002 (2011). We speculate that onset of fluctuations of nematic order on approaching the instability towards the re-entrant tetragonal phase contributes to this unusual dependence.

Do Deep Eutectic Solvents Form Uniform Mixtures Beyond Molecular Microheterogeneities?

We have performed small-angle neutron scattering in a momentum transfer range (0.05 < Q < 0.5 Å-1) to study long-range order and concentration fluctuations in deep eutectic solvents (DESs) and their aqueous solutions. Ethaline (choline chloride/ethylene glycol), glycerol/lactic acid, and menthol/decanoic acid mixtures were selected to illustrate individually the case of ionic, nonionic, and hydrophobic mixtures. Carefully designed isotopic labeling was used to emphasize selectively the spatial correlations between the different solvent components. For ethaline DESs and their aqueous solutions, a weak low-Q peak observed only for certain compositions and some partial structure factors revealed the mesoscopic segregation of ethylene glycol molecules that do not participate in the solvation of ionic units, either because they are in excess with respect to the eutectic stoichiometry (1:4 neat ethaline) or substituted by water (4w-ethaline and higher aqueous dilutions). For the nonionic hydrophilic solutions, such a mesoscopic segregation was not observed. This indicates that the better balanced interactions between the three nonionic H-bonded components (water, lactic acid, and glycerol) favor homogeneous mixing. For the hydrophobic DESs, we observed an excess of coherent scattering intensity centered at Q = 0, which could be reproduced by a model of noninteracting spherical domains. Local concentration fluctuations are not excluded either. However, unlike liquid mixtures with a tendency to demix, we have found no evidence of expansion of domains with different compositions to a large scale.

Ferrimagnetic 120∘magnetic structure inCu2OSO4

We report magnetic properties of a 3d$^9$ (Cu$^{2+}$) magnetic insulator Cu2OSO4 measured on both powder and single crystal. The magnetic atoms of this compound form layers, whose geometry can be described either as a system of chains coupled through dimers or as a Kagom\'e lattice where every 3rd spin is replaced by a dimer. Specific heat and DC-susceptibility show a magnetic transition at 20 K, which is also confirmed by neutron scattering. Magnetic entropy extracted from the specific heat data is consistent with a $S=1/2$ degree of freedom per Cu$^{2+}$, and so is the effective moment extracted from DC-susceptibility. The ground state has been identified by means of neutron diffraction on both powder and single crystal and corresponds to a $\sim120$ degree spin structure in which ferromagnetic intra-dimer alignment results in a net ferrimagnetic moment. No evidence is found for a change in lattice symmetry down to 2 K. Our results suggest that \sample \ represents a new type of model lattice with frustrated interactions where interplay between magnetic order, thermal and quantum fluctuations can be explored.