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Long-range correlation and the spin conductivity in the XXZ chain from ballistic macroscopic fluctuation theory
Authors:
Shinya Ae
Abstract:
Based on the ballistic macroscopic fluctuation theory, the integration of the spin correlation function (spin conductivity) is analyzed for the spin-1/2 XXZ chain in the critical regime. In the time when the magnetization of an infinite spin chain fluctuates from an initial state with a wavelength as long as the infinite length $N$, the equal-time two-point spin correlation function is scaled up t…
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Based on the ballistic macroscopic fluctuation theory, the integration of the spin correlation function (spin conductivity) is analyzed for the spin-1/2 XXZ chain in the critical regime. In the time when the magnetization of an infinite spin chain fluctuates from an initial state with a wavelength as long as the infinite length $N$, the equal-time two-point spin correlation function is scaled up to $O(1/N)$. In the state where the ballistic spin transport decays at high temperature $T$, the diffusive transport remains on a large scale. We show that the spin conductivity is proportional to $1/T$ in the limit $T\to\infty$ and its high temperature proportionality constant diverges in the case where one-quasiparticle magnetization is infinitely large. This analysis informs that the superdiffusive spin transport is driven by the $1/N$-scaled long-range spin correlation and sheds a light on the dynamic scaling in spin transport at the isotropic point.
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Submitted 2 May, 2026;
originally announced May 2026.
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Feedback Driven Convergence, Competition, and Entanglement in Classical Stochastic Processes
Authors:
Allen Lobo,
Saravanan A
Abstract:
We present a dynamical theory of statistical convergence in which the law of large numbers arises from outcome-outcome feedback rather than assumed independence. Defining the convergence field and its derivative, we show that empirical frequencies evolve through coupling, producing competition, finite-m fluctuations, and classical entanglement. Using the Kramers-Moyal expansion, we derive an Ito-L…
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We present a dynamical theory of statistical convergence in which the law of large numbers arises from outcome-outcome feedback rather than assumed independence. Defining the convergence field and its derivative, we show that empirical frequencies evolve through coupling, producing competition, finite-m fluctuations, and classical entanglement. Using the Kramers-Moyal expansion, we derive an Ito-Langevin and Fokker-Planck description, reducing in the symmetric regime to a time-dependent Ornstein-Uhlenbeck process. We propose variance-based witnesses that detect outcome-space entanglement in both binary sequences and coupled Brownian trajectories, and confirm entanglement through numerical experiments. Extending the formalism yields multi-outcome feedback dynamics and finite-time cross-diffusion between Brownian particles. The results unify convergence, fluctuation, and entanglement as consequences of a single feedback-driven stochastic principle.
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Submitted 24 December, 2025;
originally announced January 2026.
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Harvesting magneto-acoustic waves using magnetic two-dimensional chromium telluride (CrTe3)
Authors:
Chinmayee Chowde Gowda,
Alexey Kartsev,
Nishant Tiwari,
Suman Sarkar,
Safronov A. A,
Varun Chaudhary,
Chandra Sekhar Tiwary
Abstract:
A vast majority of electrical devices have integrated magnetic units, which generate constant magnetic fields with noticeable vibrations. The majority of existing nanogenerators acquire energy through friction/mechanical forces and most of these instances overlook acoustic vibrations and magnetic fields. Magnetic two-dimensional (2D) tellurides present a wide range of possibilities for devising a…
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A vast majority of electrical devices have integrated magnetic units, which generate constant magnetic fields with noticeable vibrations. The majority of existing nanogenerators acquire energy through friction/mechanical forces and most of these instances overlook acoustic vibrations and magnetic fields. Magnetic two-dimensional (2D) tellurides present a wide range of possibilities for devising a potential flexible energy harvester. We have synthesized two-dimensional chromium telluride (2D CrTe3) which exhibits ferromagnetic (FM) nature with a Tc of 224 K. The structure exhibits stable high remnant magnetization, making 2D CrTe3 flakes a potential material for harvesting of magneto-acoustic waves at room temperature. A magneto-acoustic nanogenerator (MANG) was fabricated composing of 2D CrTe3 dispersed in a polymer matrix. Basic mechanical stability and sensitivity of the device with change in load conditions were tested. A high surface charge density of 2.919 mC m-2 was obtained for the device. The thermal strain created in the lattice structure was examined using in-situ Raman spectroscopic measurements. The magnetic anisotropy energy (MAE) responsible for long-range FM ordering was calculated with the help of theoretical modelling. The theoretical calculations also showed opening of electronic bandgap which enhances the flexoelectric effects. The MANG can be a potential energy harvester to synergistically tap into the magneto-acoustic vibrations generated from the frequency changes of a vibrating device such as loudspeakers.
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Submitted 21 June, 2024;
originally announced June 2024.
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Non-thermal Magnetic Deicing Using Two-Dimensional Chromium Telluride
Authors:
Chinmayee Chowde Gowda,
Alexey Kartsev,
Nishant Tiwari,
Safronov A. A,
Prafull Pandey,
Ajit K. Roy,
Pulickel M. Ajayan,
Douglas S. Galvao,
Chandra Sekhar Tiwary
Abstract:
Two-dimensional (2D) chromium telluride Cr2Te3 exhibits strong ferromagnetic ordering with high coercivity at low temperatures and paramagnetic behaviour when approaching room temperature. The spin states of monolayer Cr2Te3 show ferromagnetic ordering in the ground state, and in-situ Raman analysis shows reversible structure transformation and hence a ferromagnetic to paramagnetic transition duri…
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Two-dimensional (2D) chromium telluride Cr2Te3 exhibits strong ferromagnetic ordering with high coercivity at low temperatures and paramagnetic behaviour when approaching room temperature. The spin states of monolayer Cr2Te3 show ferromagnetic ordering in the ground state, and in-situ Raman analysis shows reversible structure transformation and hence a ferromagnetic to paramagnetic transition during low-temperature heating cycles (0 - 25 °C). The magnetic phase transition near room temperature in the 2D Cr2Te3 prompted the exploration of these layered materials for energy application. We demonstrate that the low-temperature ferromagnetic behavior can be used to magnetically deice material surfaces using an external magnetic source, avoiding the use of harsh chemicals and high temperatures. The hydrophobic nature and dipole interactions of H2O molecules with the surface of the 2D Cr2Te3 coating aid in the condensation of ice droplets formed on the surface. First-principles calculations also confirm the observed crystal structure, surface interaction, and magnetic properties of 2D Cr2Te3.
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Submitted 20 June, 2024;
originally announced June 2024.
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Radiation resistance of fine-grained ceramics Y2.5Nd0.5Al5O12 under Xe-ions irradiation
Authors:
Alekseeva L. S.,
Nokhrin A. V.,
Yunin P. A.,
Nazarov A. A.,
Orlova A. I.,
Skuratov V. A.,
Issatov A. T.,
Kovylin R. S.,
Murashov A. A.,
Boldin M. S.,
Voronin A. V.,
Chuvil'deev V. N.,
Zotov D. A.
Abstract:
Oxide Y2.5Nd0.5Al5O12 (YAG:Nd) with garnet structure was synthesized in the powder and ceramics forms. Fine-grained YAG:Nd ceramics with a relative density of ~99% were obtained by the Spark Plasma Sintering method (SPS). The radiation resistance of ceramics was studied under irradiation with swift Xe-ions (E = 146 MeV). A gradient defect structure is formed in irradiated ceramics, varying from la…
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Oxide Y2.5Nd0.5Al5O12 (YAG:Nd) with garnet structure was synthesized in the powder and ceramics forms. Fine-grained YAG:Nd ceramics with a relative density of ~99% were obtained by the Spark Plasma Sintering method (SPS). The radiation resistance of ceramics was studied under irradiation with swift Xe-ions (E = 146 MeV). A gradient defect structure is formed in irradiated ceramics, varying from layer to layer. The strained YAG phase formed as a result of Xe ions irradiation is localized in a near-surface layer with a thickness of ~5 μm. Full amorphization of the samples was observed under irradiation with a fluence of 1x10^13 cm-2. The calculated critical fluence was 6.5x10^12 cm-2, which corresponded to 0.03 dpa. The microhardness of the surface layers of irradiated ceramics is less than the central layers, and, in general, decreases with increasing ion fluence.
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Submitted 10 December, 2023;
originally announced December 2023.
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Infinite temperature spin dc conductivity of the spin-1/2 XXZ chain
Authors:
Shinya Ae
Abstract:
Using the Bethe ansatz method and the TBA equations for the higher spin integrable XXZ chain, the regular zero frequency contribution to the spin current correlation (spin dc conductivity) is analyzed for the spin-1/2 XXZ chain with an anisotropy $0 \le Δ<1$. In the high temperature limit, we write down the dressed scattering kernels by one quasi-particle bare energies, which allows the exact eval…
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Using the Bethe ansatz method and the TBA equations for the higher spin integrable XXZ chain, the regular zero frequency contribution to the spin current correlation (spin dc conductivity) is analyzed for the spin-1/2 XXZ chain with an anisotropy $0 \le Δ<1$. In the high temperature limit, we write down the dressed scattering kernels by one quasi-particle bare energies, which allows the exact evaluation of the infinite temperature spin dc conductivity $\mathcal{L}$. We find that $\mathcal{L}$ is discontinuous at all rational numbers of the anisotropy parameter $p_0=π/\cos^{-1}Δ$ in the region $p_0 \ge 2$ with the gap increasing larger than the second power of growing magnetization on one quasi-particle. The isotropic $Δ=1$ point is exceptional. Close to this point, $\mathcal{L}$ slowly increases in proportion to the first power of the magnetization. On the other hand $\mathcal{L}$ is proportional to the second power of the magnetization when $p_0$ approaches irrational numbers.
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Submitted 29 April, 2024; v1 submitted 7 October, 2023;
originally announced October 2023.
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Spin Drude weight for the integrable XXZ chain with arbitrary spin
Authors:
Shinya Ae,
Kazumitsu Sakai
Abstract:
Using generalized hydrodynamics (GHD), we exactly evaluate the finite-temperature spin Drude weight at zero magnetic field for the integrable XXZ chain with arbitrary spin and easy-plane anisotropy. First, we construct the fusion hierarchy of the quantum transfer matrices ($T$-functions) and derive functional relations ($T$- and $Y$-systems) satisfied by the $T$-functions and certain combinations…
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Using generalized hydrodynamics (GHD), we exactly evaluate the finite-temperature spin Drude weight at zero magnetic field for the integrable XXZ chain with arbitrary spin and easy-plane anisotropy. First, we construct the fusion hierarchy of the quantum transfer matrices ($T$-functions) and derive functional relations ($T$- and $Y$-systems) satisfied by the $T$-functions and certain combinations of them ($Y$-functions). Through analytical arguments, the $Y$-system is reduced to a set of non-linear integral equations, equivalent to the thermodynamic Bethe ansatz (TBA) equations. Then, employing GHD, we calculate the spin Drude weight at arbitrary finite temperatures. As a result, a characteristic fractal-like structure of the Drude weight is observed at arbitrary spin, similar to the spin-1/2 case. In our approach, the solutions to the TBA equations (i.e., the $Y$-functions) can be explicitly written in terms of the $T$-functions, thus allowing for a systematic calculation of the high-temperature limit of the Drude weight.
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Submitted 30 January, 2024; v1 submitted 28 September, 2023;
originally announced September 2023.
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Ultrasensitive Field-Effect Biosensors Enabled by the Unique Electronic Properties of Graphene
Authors:
Xiaoyan Zhang,
Qiushi Jing,
Shen Ao,
Grégory F. Schneider,
Dmitry Kireev,
Zhengjun Zhang,
Wangyang Fu
Abstract:
This review provides a critical overview of current developments on nanoelectronic biochemical sensors based on graphene. Composed of a single layer of conjugated carbon atoms, graphene has outstanding high carrier mobility and low intrinsic electrical noise, but a chemically inert surface. Surface functionalization is therefore crucial to unravel graphene sensitivity and selectivity for the detec…
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This review provides a critical overview of current developments on nanoelectronic biochemical sensors based on graphene. Composed of a single layer of conjugated carbon atoms, graphene has outstanding high carrier mobility and low intrinsic electrical noise, but a chemically inert surface. Surface functionalization is therefore crucial to unravel graphene sensitivity and selectivity for the detection of targeted analytes. To achieve optimal performance of graphene transistors for biochemical sensing, the tuning of the graphene surface properties via surface functionalization and passivation is highlighted, as well as the tuning of its electrical operation by utilizing multifrequency ambipolar configuration and a high frequency measurement scheme to overcome the Debye screening to achieve low noise and highly sensitive detection. Potential applications and prospectives of ultrasensitive graphene electronic biochemical sensors ranging from environmental monitoring and food safety, healthcare and medical diagnosis, to life science research, are presented as well.
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Submitted 10 December, 2020;
originally announced December 2020.
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Electrical probing of COVID-19 spike protein receptor binding domain via a graphene field-effect transistor
Authors:
Xiaoyan Zhang,
Qige Qi,
Qiushi Jing,
Shen Ao,
Zhihong Zhang,
Mingchao Ding,
Muhong Wu,
Kaihui Liu,
Weipeng Wang,
Yunhan Ling,
Zhengjun Zhang,
Wangyang Fu
Abstract:
Here, in an effort towards facile and fast screening/diagnosis of novel coronavirus disease 2019 (COVID-19), we combined the unprecedently sensitive graphene field-effect transistor (Gr-FET) with highly selective antibody-antigen interaction to develop a coronavirus immunosensor. The Gr-FET immunosensors can rapidly identify (about 2 mins) and accurately capture the COVID-19 spike protein S1 (whic…
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Here, in an effort towards facile and fast screening/diagnosis of novel coronavirus disease 2019 (COVID-19), we combined the unprecedently sensitive graphene field-effect transistor (Gr-FET) with highly selective antibody-antigen interaction to develop a coronavirus immunosensor. The Gr-FET immunosensors can rapidly identify (about 2 mins) and accurately capture the COVID-19 spike protein S1 (which contains a receptor binding domain, RBD) at a limit of detection down to 0.2 pM, in a real-time and label-free manner. Further results ensure that the Gr-FET immunosensors can be promisingly applied to screen for high-affinity antibodies (with binding constant up to 2*10^11 M^-1 against the RBD) at concentrations down to 0.1 pM. Thus, our developed electrical Gr-FET immunosensors provide an appealing alternative to address the early screening/diagnosis as well as the analysis and rational design of neutralizing-antibody locking methods of this ongoing public health crisis.
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Submitted 27 March, 2020;
originally announced March 2020.
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Calculated high-pressure structural properties, lattice dynamics and quasi particle band structures of perovskite fluorides KZnF 3 , CsCaF 3 and BaLiF 3
Authors:
Vaitheeswaran G,
Kanchana V,
Zhang X,
Ma Y,
Svane A,
Christensen NE
Abstract:
A detailed study of the high-pressure structural properties, lattice dynamics and band structures of perovskite structured fluorides KZnF3, CsCaF3 and BaLiF3 has been carried out by means of density functional theory. The calculated structural properties including elastic constants and equation of state agree well with available experimental information. The phonon dispersion curves are in good ag…
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A detailed study of the high-pressure structural properties, lattice dynamics and band structures of perovskite structured fluorides KZnF3, CsCaF3 and BaLiF3 has been carried out by means of density functional theory. The calculated structural properties including elastic constants and equation of state agree well with available experimental information. The phonon dispersion curves are in good agreement with available experimental inelastic neutron scattering data. The electronic structures of these fluorides have been calculated using the quasi particle self-consistent [Formula: see text] approximation. The [Formula: see text] calculations reveal that all the fluorides studied are wide band gap insulators, and the band gaps are significantly larger than those obtained by the standard local density approximation, thus emphasizing the importance of quasi particle corrections in perovskite fluorides.
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Submitted 2 September, 2016;
originally announced September 2016.
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Trouble with the Drude theory of metallic conduction: Incompatibility with special relativity
Authors:
Sree Harsha N R,
Anupama Prakash,
Sreedevi A,
Kothari D P
Abstract:
In this paper, we show that the classical Drude model of electrical conductivity, one of the fundamental models in the theory of electrical conductivity, is inconsistent with the special relativity. Due to this incorrect model, a current carrying closed circuit is thought not to produce second order electric field according to Maxwell's theory of electromagnetism. But, Edwards et al. detected a sm…
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In this paper, we show that the classical Drude model of electrical conductivity, one of the fundamental models in the theory of electrical conductivity, is inconsistent with the special relativity. Due to this incorrect model, a current carrying closed circuit is thought not to produce second order electric field according to Maxwell's theory of electromagnetism. But, Edwards et al. detected a small second order electric field radially pointing toward a current carrying conductor in a superconducting Nb-Ti coil. Assis et al. claim to show that Maxwell's theory does not predict any second order forces and hence we should take Weber's electrodynamics seriously. But, we show that not only a magnetic field, but also a second order electric field is produced in the vicinity of a current carrying conductor, which is consistent with Maxwell's theory. This electric field points radially toward the current carrying conductor as detected in Edwards' experiments. We also show that the positive field, detected by Sansbury in a U-shaped copper conductor carrying a constant current, should be created as a consequence of our theory. We then estimate the order of the strength of this electric field and show that it is in agreement with the experimental values.
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Submitted 8 February, 2016;
originally announced February 2016.
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The Dzyaloshinskii-Moriya interaction is under control: an orchestrated flip of the chiral link between structure and magnetism for Fe$_{1-x}$Co$_x$Si
Authors:
S. -A. Siegfried,
E. V. Altynbaev,
N. M. Chubova,
V. Dyadkin,
D. Chernyshov,
E. V. Moskvin,
D. Menzel,
A. Heinemann,
A. Schreyer A.,
S. V. Grigoriev
Abstract:
Monosilicides of 3d-metals frequently show a chiral magnetic ordering with the absolute configuration defined by the chirality of the crystal structure and the sign of the Dzyaloshinskii-Moriya interaction (DMI). Structural and magnetic chiralities are probed here for Fe$_{1-x}$Co$_x$Si series and their mutual relationship is found to be dependent on the chemical composition. The chirality of crys…
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Monosilicides of 3d-metals frequently show a chiral magnetic ordering with the absolute configuration defined by the chirality of the crystal structure and the sign of the Dzyaloshinskii-Moriya interaction (DMI). Structural and magnetic chiralities are probed here for Fe$_{1-x}$Co$_x$Si series and their mutual relationship is found to be dependent on the chemical composition. The chirality of crystal structure was previously shown to be governed by crystal growth, and the value of the DMI is nearly the same for all monosilicides of Fe, Co and Mn. Our findings indicate that the sign of the DMI in Fe$_{1-x}$Co$_x$Si is controlled by the Co composition $x$, thus, opening a route towards controlled design of chiral spintronics devices.
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Submitted 9 April, 2015; v1 submitted 25 March, 2015;
originally announced March 2015.