Divergence Of Susceptibility Research Articles

Direct visualization and control of antiferromagnetic domains and spin reorientation in a parent cuprate

We report magnetic optical second-harmonic generation (SHG) polarimetry and imaging on Sr$_2$Cu$_3$O$_4$Cl$_2$, which allows direct visualization of the mesoscopic antiferromagnetic (AFM) structure of a parent cuprate. Temperature- and magnetic-field-dependent SHG reveals large domains with 90$^{\circ}$ relative orientations that are stabilized by a combination of uniaxial magnetic anisotropy and the Earth's magnetic field. Below a temperature $T_R$ $\sim$ 97 K, we observe an unusual 90$^{\circ}$ spin reorientation transition, possibly driven by competing magnetic anisotropies of the two copper sublattices, which swaps the AFM domain states while preserving the domain structure. This allows deterministic switching of the AFM states by thermal or laser heating. Near $T_R$, the domain walls become exceptionally responsive to an applied magnetic field, with the Earth's field sufficient to completely expel them from the crystal. Our findings unlock opportunities to study the mesoscopic AFM behavior of parent cuprates and explore their potential for AFM technologies.

First-Principles Study of the RKKY Interaction and the Quadrupole Order in the Pr 1-2-20 Systems PrT2Al20 (T = Ti, V)

Electronic states and quadrupole orders in the Pr 1-2-20 systems PrT2Al20 (T=Ti, V) are investigated on the basis of the first-principles calculations. The effective 196 orbital model is derived to reproduce the first-principles electronic structures of LaT2Al20 (T=Ti, V) without contribution from the Pr 4f electrons which are considered to be well localized and is employed to calculate the Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions between quadrupole and octupole moments of the Pr ions. Within the random phase approximation for the RKKY Hamiltonian, the most divergent susceptibility is found to be the quadrupole one for the wave vector Q = (0,0,0) in the case of PrTi2Al20 while that for Q = (pi/a,0,pi/a) in the case of PrV2Al20 as consistent with experimental observations in the both cases which exhibit the ferro-quadrupole (FQ) and the antiferro-quadrupole (AFQ) orders, respectively. We also discuss the ordered states using the mean-field approximation and find that, in the case of PrTi2Al20, the 1st-order phase transition to the O20 FQ order with a tiny discontinuity takes place as predicted by the Landau theory. In the case of PrV2Al20, the system exhibits two distinct O22 AFQ orders, AFQ-I and AFQ-II, and shows subsequent two phase transitions, the 2nd-order one from normal to AFQ-I and the 1st-order one from AFQ-I to AFQ-II, that may be responsible for the double transitions observed by specific heat measurements.

Anomalous broadening of Landau levels at the saddle point energy of two dimensional square lattice

We study the magnetic characteristics of the two dimensional (2D) square lattice with one valence electron per lattice site in weak rational magnetic fields accessible experimentally, by solving numerically the exact system of discrete equations, which fully describes the broadening of Landau levels. The 2D square lattice is used as a prototype electron system in which the Fermi level lies at the energy of the saddle point (Van Hove peak) of the Brillouin zone and the corresponding density of states N(EF) is formally infinite (N(EF)→+∞). According to the electron band treatment this could lead to a formally divergent paramagnetic susceptibility and an infinite electron contribution to the specific heat at zero temperature, but our accurate analysis shows that both values remain finite. The energy spectrum of the Landau level at the saddle point has turned out to be principally continuous, so that even in a very small magnetic field this Landau level is always broadened in a miniband, in contrast to other energies, where the spectrum of Landau levels is discrete. Taking into account the electron spin polarization and the numerical solution, we reproduce the temperature dependence of the induced magnetic moment proportional to the magnetic susceptibility, and the electron contribution to the specific heat. Both plots demonstrate unusual dependencies reflecting the “metal”-like or “insulator”-like structure of the Landau minibands in the neighborhood of the Fermi energy. At low temperatures all values display oscillatory behavior. We also prove rigorously that the fully occupied electron band has no contribution to the diamagnetic susceptibility and specific heat.

Magnetoelectric coupling on fused azulene oligomers

The global magnetic phase diagram for fused azulene oligomers is obtained by using a fermionic Hubbard model, which is an intermediate between the molecular Pariser-Parr-Pople empiric Hamiltonian and the spin-$1/2$ antiferromagnetic Heisenberg model. We employ the density matrix renormalization group (DMRG) approach to explore the ground state properties of azulene-like molecules as a function of the electronic correlation and the oligomer size. It is shown that, depending on the length of the oligomer, fused azulene transitions from a singlet ($S=0$) to a higher-spin ($S=1,2$) ground state. Near the quantum magnetic phase transition the electric dipole moment, present on fused azulene molecules, couples with the magnetic moment leading to a divergent magnetoelectric susceptibility at the boundary lines of the magnetic phase diagram. These spontaneous electric and magnetic polarizations, together with the magnetoelectric coupling between them, indeed corroborate that these fused azulene oligomers can be viewed as a purely organic multiferroic material, being a magnetoelectric molecule.

Nucleoside analogues for the treatment of animal trypanosomiasis

Animal trypanosomiasis (AT) is a parasitic disease with high socio-economic impact. Given the limited therapeutic options and problems of toxicity and drug resistance, this study assessed redirecting our previously identified antitrypanosomal nucleosides for the treatment of AT. Promising hits were identified with excellent in vitro activity across all important animal trypanosome species. Compound 7, an inosine analogue, and our previously described lead compound, 3′-deoxytubercidin (8), showed broad spectrum anti-AT activity, metabolic stability in the target host species and absence of toxicity, but with variable efficacy ranging from limited activity to full cure in mouse models of Trypanosoma congolense and T. vivax infection. Several compounds show promise against T. evansi (surra) and T. equiperdum (dourine). Given the preferred target product profile for a broad-spectrum compound against AT, this study emphasizes the need to include T. vivax in the screening cascade given its divergent susceptibility profile and provides a basis for lead optimization towards such broad spectrum anti-AT compound.

The Opportunity of Proteomics to Advance the Understanding of Intra- and Extracellular Regulation of Malignant Hematopoiesis.

Fetal and adult hematopoiesis are regulated by largely distinct sets of cell-intrinsic gene regulatory networks as well as extracellular cues in their respective microenvironment. These ontogeny-specific programs drive hematopoietic stem and progenitor cells (HSPCs) in fetus and adult to divergent susceptibility to initiation and progression of hematological malignancies, such as leukemia. Elucidating how leukemogenic hits disturb the intra- and extracellular programs in HSPCs along ontogeny will provide a better understanding of the causes for age-associated differences in malignant hematopoiesis and facilitate the improvement of strategies for prevention and treatment of pediatric and adult acute leukemia. Here, we review current knowledge of the intrinsic and extrinsic programs regulating normal and malignant hematopoiesis, with a particular focus on the differences between infant and adult acute leukemia. We discuss the recent advances in mass spectrometry-based proteomics and its opportunity for resolving the interplay of cell-intrinsic and niche-associated factors in regulating malignant hematopoiesis.

Superconducting and chiral-glass to insulator transition in phase-glass models in a magnetic field

We investigate the quantum phase transitions of a phase-glass model in a magnetic field with frustration parameter f = 1/2, describing the effects random negative Josephson-junction couplings in two-dimensional superconductors. The critical behavior is obtained by a scaling analysis of path-integral Monte Carlo simulations at zero temperature, including corrections to finite-size scaling. A single superconducting and chiral-glass to insulator transition occurs above a disorder threshold with divergent nonlinear magnetic susceptibility, unaffected by the additional magnetic-field frustration. The relevance of this transition for nanohole superconducting thin films doped with magnetic impurities is discussed.

Pair-density-wave in the strong coupling limit of the Holstein-Hubbard model

A pair-density-wave (PDW) is a superconducting state with an oscillating order parameter. A microscopic mechanism that can give rise to it has been long sought but has not yet been established by any controlled calculation. Here we report a density-matrix renormalization-group (DMRG) study of an effective t-J-V model, which is equivalent to the Holstein-Hubbard model in a strong-coupling limit, on long two-, four-, and six-leg triangular cylinders. While a state with long-range PDW order is precluded in one dimension, we find strong quasi-long-range PDW order with a divergent PDW susceptibility as well as the spontaneous breaking of time-reversal and inversion symmetries. Despite the strong interactions, the underlying Fermi surfaces and electron pockets around the K and {K}^{prime} points in the Brillouin zone can be identified. We conclude that the state is valley-polarized and that the PDW arises from intra-pocket pairing with an incommensurate center of mass momentum. In the two-leg case, the exponential decay of spin correlations and the measured central charge c ≈ 1 are consistent with an unusual realization of a Luther-Emery liquid.

Ising-like Critical Behavior of Vortex Lattices in an Active Fluid.

Turbulent vortex structures emerging in bacterial active fluids can be organized into regular vortex lattices by weak geometrical constraints such as obstacles. Here we show, using a continuum-theoretical approach, that the formation and destruction of these patterns exhibit features of a continuous second-order equilibrium phase transition, including long-range correlations, divergent susceptibility, and critical slowing down. The emerging vorticity field can be mapped onto a two-dimensional (2D) Ising model with antiferromagnetic nearest-neighbor interactions by coarse graining. The resulting effective temperature is found to be proportional to the strength of the nonlinear advection in the continuum model.

Different wild type strains of zebrafish show divergent susceptibility to TNBS-induced intestinal inflammation displaying distinct immune cell profiles

Little is known about the diversity in immune profile of the different wild type strains of zebrafish (Danio rerio), despite its growing popularity as an animal model to study human diseases and drug testing. In the case of data resulting from modeling human diseases, differences in the background Danio fishes have rarely been taken into consideration when interpreting results and this is potentially problematic, as many studies not even mention the source and strain of the animals. In this study, we hypothesized that different wild type zebrafish strains could present distinct immune traits. To address the differences in immune responses between two commonly used wild type strains of zebrafish, AB and Tübingen (TU), we used an intestinal inflammation model induced by 2,4,6-Trinitrobenzenesulfonic acid (TNBS) and characterized the susceptibility and immune profile in these two strains. Our data demonstrates significant differences in survival between AB and TU strains when exposed to TNBS, suggesting important physiological differences in how these strains respond to inflammatory challenges. We observed that the AB strain presented increased mortality, higher neutrophilic intestinal infiltration, decreased goblet cell numbers and decreased IL-10 expression when exposed to TNBS, compared to the TU strain. In summary, our study demonstrates strain-specific immunological responses in AB and TU animals. Finally, the significant variations in strain-related susceptibility to inflammation and the differences in the immune profile shown here, highlight that the background of each strain need to be considered when utilizing zebrafish to model diseases and for drug screening purposes, thus better immune characterization of the diverse wild type strains of zebrafish is imperative.

Pauli paramagnetism of triplet Cooper pairs in a nematic superconductor

We investigate the response of a doped topological insulator ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$ with spin-triplet nematic superconductivity to external magnetization. We calculate the Zeeman part of the magnetic susceptibility for nematic and chiral superconducting phases near ${T}_{c}$ in the Ginzburg-Landau formalism. The superconducting order parameter from the ${E}_{u}$ representation has nontrivial coupling with the transversal Zeeman field that results in a paramagnetic response to magnetization. The topology of a Fermi surface has a strong influence on magnetic susceptibility. The Lifshitz transition from a closed to open Fermi surface eventually leads to a phase transition from the nematic to chiral phase. At the transition point, magnetic susceptibility diverges. Also, we study the effects of the electron-electron interaction on the competition between nematic and chiral phases. We find that in a real system, electron-electron interaction can drive the nematic to chiral phase only in the vicinity of the phase transition. We compare our results with the existing experimental data.

Genome-wide association of individual vulnerability with alcohol-associated liver disease: A Korean genome and epidemiology study.

Background and aimsThe quantity of alcohol leading to alcohol‐associated liver disease (ALD) varies individually. Genetic backgrounds contributing to the divergence in individual susceptibility to alcohol‐induced liver damage have not been elucidated in detail.Approach and resultsBased on the Korean Genome and Epidemiology Study Health Examination (KoGES_HEXA) cohort data, 21,919 participants (40‐79 years old) were included and divided into cases and controls based on the ALD diagnostic criteria proposed by the American College of Gastroenterology. Data generated by a genome wide‐association study were analyzed using logistic regression to assess the risk of ALD development in nondrinkers, light drinkers, and heavy drinkers. We detected three loci, gamma‐glutamyltransferase 1 (GGT1), zinc protein finger 827 (ZNF827) and HNF1 homeobox A (HNF1A), which were significantly associated with ALD risk. The GGT1 rs2006227 minor allele was strongly associated with all groups. Among the minor alleles of single nucleotide polymorphisms (SNPs) in HNF1A, rs1183910 had the strongest association with a protective effect from ALD in light drinkers. However, this association was not observed in heavy drinkers. Five SNPs on chromosome 11 showed suggestive significance in protective effects against ALD.ConclusionsSNPs, including HNF1A rs1183910 minor allele, are the most promising genetic candidates for protection against ALD. The expression of genes contributing to ALD development may be altered by the amount of alcohol consumed.

Critical dielectric susceptibility at a magnetic BEC quantum critical point

Magnetic-field-induced phase transitions are investigated in the frustrated gapped quantum paramagnet Rb$_{2}$Cu$_{2}$Mo$_3$O$_{12}$ through dielectric and calorimetric measurements on single-crystal samples. It is clarified that the previously reported dielectric anomaly at 8~K in powder samples is not due to a chiral spin liquid state as has been suggested, but rather to a tiny amount of a ferroelectric impurity phase. Two field-induced quantum phase transitions between paraelectric and paramagnetic and ferroelectric and magnetically ordered states are clearly observed. It is shown that the electric polarization is a secondary order parameter at the lower-field (gap closure) quantum critical point but a primary one at the saturation transition. Having clearly identified the magnetic Bose-Einstein condensation (BEC) nature of the latter, we use the dielectric channel to directly measure the critical divergence of BEC susceptibility. The observed power-law behavior is in very good agreement with theoretical expectations for three-dimensional BEC. Finally, dielectric data reveal magnetic presaturation phases in this compound that may feature exotic order with unconventional broken symmetries.

Integrative biology defines novel biomarkers of resistance to strongylid infection in horses

The widespread failure of anthelmintic drugs against nematodes of veterinary interest requires novel control strategies. Selective treatment of the most susceptible individuals could reduce drug selection pressure but requires appropriate biomarkers of the intrinsic susceptibility potential. To date, this has been missing in livestock species. Here, we selected Welsh ponies with divergent intrinsic susceptibility (measured by their egg excretion levels) to cyathostomin infection and found that their divergence was sustained across a 10-year time window. Using this unique set of individuals, we monitored variations in their blood cell populations, plasma metabolites and faecal microbiota over a grazing season to isolate core differences between their respective responses under worm-free or natural infection conditions. Our analyses identified the concomitant rise in plasma phenylalanine level and faecal Prevotella abundance and the reduction in circulating monocyte counts as biomarkers of the need for drug treatment (egg excretion above 200 eggs/g). This biological signal was replicated in other independent populations. We also unravelled an immunometabolic network encompassing plasma beta-hydroxybutyrate level, short-chain fatty acid producing bacteria and circulating neutrophils that forms the discriminant baseline between susceptible and resistant individuals. Altogether our observations open new perspectives on the susceptibility of equids to strongylid infection and leave scope for both new biomarkers of infection and nutritional intervention.

Clusters and avalanches of fibre breaks in a model of an impregnated unidirectional fibre bundle under tension

Development of clusters and avalanches of damage events is a key characteristic in statistical physics of structures susceptible to a catastrophic failure. This paper applies the concepts of such descriptions to the process of fibre breakage under tension in an impregnated fibre bundle model (IFBM). The following parameters are analysed: (1) susceptibility (damage caused by change in loading); (2) spatial clustering of breaks and its interdependency with avalanches; (3) the size distribution of fibre break clusters and avalanches; (4) fractal dimensions; and (5) correlation lengths of breaks. A systematic workflow and algorithms for this analysis are presented and applied for two realisations of a random fibre placement of carbon fibre/epoxy bundles with fibre volume fractions of 50% and 60%. For these two realisations: (1) the susceptibility divergence near the failure point is affected by the finite-size effect, being nearly constant for the last ~1/20th of strain life; this behaviour can be considered as a failure predictor; (2) the morphology of the break system is a spatially distributed multi-defect occurrence with the dimensionality of 3 for all breaks together and weak planarity demonstrated only by the largest clusters near failure; (3) the exponents of the cluster-size and avalanche-size power law distributions reached 2.5–3 for both statistics near the bundle failure, which may constitute an imminent failure indicator. Damage evolution of the carbon/epoxy IFBM up to the final failure is found to be short-correlated (with correlation length of the order of one fibre break stress redistribution zone) in the absence of collective long-range defect interactions. During the catastrophic avalanche, the spatially distributed morphology of breaks is gradually reorganized into a translaminar fracture mode.

Spectral phase transitions in optical parametric oscillators

Driven nonlinear resonators provide a fertile ground for phenomena related to phase transitions far from equilibrium, which can open opportunities unattainable in their linear counterparts. Here, we show that optical parametric oscillators (OPOs) can undergo second-order phase transitions in the spectral domain between degenerate and non-degenerate regimes. This abrupt change in the spectral response follows a square-root dependence around the critical point, exhibiting high sensitivity to parameter variation akin to systems around an exceptional point. We experimentally demonstrate such a phase transition in a quadratic OPO. We show that the divergent susceptibility of the critical point is accompanied by spontaneous symmetry breaking and distinct phase noise properties in the two regimes, indicating the importance of a beyond nonlinear bifurcation interpretation. We also predict the occurrence of first-order spectral phase transitions in coupled OPOs. Our results on non-equilibrium spectral behaviors can be utilized for enhanced sensing, advanced computing, and quantum information processing.

θdependence in the small-Nlimit of2dCPN−1models

We present a systematic numerical study of $\theta$-dependence around $\theta=0$ in the small-$N$ limit of $2d$ $CP^{N-1}$ models, aimed at clarifying the possible presence of a divergent topological susceptibility in the continuum limit. We follow a twofold strategy, based on one side on direct simulations for $N = 2$ and $N = 3$ on lattices with correlation lengths up to $O(10^2)$, and on the other side on the small-$N$ extrapolation of results obtained for $N$ up to $9$. Based on that, we provide conclusive evidence for a finite topological susceptibility at $N = 3$, with a continuum estimate $\xi^2 \chi = 0.110(5)$. On the other hand, results obtained for $N = 2$ are still inconclusive: they are consistent with a logarithmically divergent continuum extrapolation, but do not yet exclude a finite continuum value, $\xi^2 \chi \sim 0.4$, with the divergence taking place for $N$ slightly below 2 in this case. Finally, results obtained for the non-quadratic part of $\theta$-dependence, in particular for the so-called $b_2$ coefficient, are consistent with a $\theta$-dependence matching that of the Dilute Instanton Gas Approximation at the point where $\xi^2 \chi$ diverges.

Dominant In-Plane Symmetric Elastoresistance in CsFe_{2}As_{2}.

We study the elastoresistance of the highly correlated material CsFe_{2}As_{2} in all symmetry channels. Neutralizing its thermal expansion by means of a piezoelectric-based strain cell is demonstrated to be essential. The elastoresistance response in the in-plane symmetric channel is found to be large, while the response in the symmetry-breaking channels is weaker and provides no evidence for a divergent nematic susceptibility. Rather, our results can be interpreted naturally within the framework of a coherence-incoherence crossover, where the low-temperature coherent state is sensitively tuned by the in-plane atomic distances.

Characterization of a continuous phase transition in a chaotic system

Some characteristics of scaling invariance are discussed for a transition from integrability to non-integrability in a class of dynamical systems described by a two-dimensional, nonlinear and area-preserving mapping. The dynamical variables are action I and angle θ and that the angle diverges in the limit of vanishingly action. The transition is controlled by a parameter ϵ closely related to the order parameter. A scaling invariance observed for the average squared action along the chaotic sea gives evidence that the transition observed from integrability to non-integrability is equivalent to a second-order, also called continuous, phase transition since when the order parameter approaches zero at the same time the response of the order parameter to the conjugate field (susceptibility) diverges. This investigation allows application to a wide class of systems and transitions, including transition from limited to unlimited chaotic diffusion in dissipative systems and also in a transition from limited to unlimited Fermi acceleration in time-dependent billiard systems.

Divergent Nematic Susceptibility near the Pseudogap Critical Point in a Cuprate Superconductor

Superconductivity is a quantum phenomenon caused by bound pairs of electrons. In diverse families of strongly correlated electron systems, the electron pairs are not bound together by phonon exchange but instead by some other kind of bosonic fluctuations. In these systems, superconductivity is often found near a magnetic quantum critical point (QCP) where a magnetic phase vanishes in the zero-temperature limit. Moreover, the maximum of superconducting transition temperature Tc frequently locates near the magnetic QCP, suggesting that the proliferation of critical spin fluctuations emanating from the QCP plays an important role in Cooper pairing. In cuprate superconductors, however, the superconducting dome is usually separated from the antiferromagnetic phase and Tc attains its maximum value near the verge of enigmatic pseudogap state that appears below doping-dependent temperature T*. Thus a clue to the pairing mechanism resides in the pseudogap and associated anomalous transport properties. Recent experiments suggested a phase transition at T*, yet, most importantly, relevant fluctuations associated with the pseudogap have not been identified. Here we report on direct observations of enhanced nematic fluctuations in (Bi,Pb)2Sr2CaCu2O8+d by elastoresistance measurements, which couple to twofold in-plane electronic anisotropy, i.e. electronic nematicity. The nematic susceptibility shows Curie-Weiss-like temperature dependence above T*, and an anomaly at T* evidences a second-order transition with broken rotational symmetry. Near the pseudogap end point, where Tc is not far from its peak in the superconducting dome, nematic susceptibility becomes singular and divergent, indicating the presence of a nematic QCP. This signifies quantum critical fluctuations of a nematic order, which has emerging links to the high-Tc superconductivity and strange metallic behaviours in cuprates.