Magnetic Regime Research Articles

Electronic and magnetic phase diagram of Sr2FeO4 at high pressure: A synchrotron Mössbauer study

Transition metal (TM) oxides with high oxidation state TM ions exhibit a variety of unconventional electronic and magnetic states owing to electron correlations effects combined with highly covalent TM–O bonding. Here, we have studied the pressure dependence of electronic state and magnetism of the K2NiF4-type iron(IV) oxide Sr2FeO4 up to 89 GPa by temperature and magnetic field dependent energy-domain synchrotron Mössbauer spectroscopy and derived a (P,T) magnetic phase diagram. Considering also previous resistance studies [Rozenberg , ] several magnetic and electronic regimes with increasing pressure can be identified. Near 7 GPa, the insulating cycloidal antiferromagnetic low-P state is transformed into a semiconducting ferromagnetic state and the magnetic ordering temperature Tm increases from 55 K at ambient pressure to about 100 K at 13 GPa. Between 18 and about 50 GPa the system is ferromagnetic and metallic (FMM) with a strong rise of Tm to above room temperature (RT). Contrary to a recent theoretical study [Kazemi-Moridani , ], the FMM state is attributed to a high-spin t2g3eg1 electronic state with itinerant eg coupled to more localized t2g electrons. Between 50 and 89 GPa a doublet with large quadrupole splitting in the RT Mössbauer spectra indicates a partial high-spin to low-spin (t2g4) transition leading to a decrease in Tm again. The general features of the (P,T) phase diagram of Sr2FeO4 are comparable to those of other simple and A-site ordered iron(IV) perovskite-related oxides with the peculiarity that Sr2FeO4 adopts an insulating state without charge disproportionation of Fe4+ in the low-P region. The high-pressure behavior of Sr2FeO4 and other iron(IV) oxides may be relevant for exploring the role of Hund's physics in multiorbital systems and contributing to the understanding of the electronic situation in unconventional superconductors such as La3Ni2O7 and Sr2RuO4. Published by the American Physical Society 2024

Integration of photomagnetic bimodal imaging to monitor an autogenous exosome loaded platform: unveiling strong targeted retention effects for guiding the photothermal and magnetothermal therapy in a mouse prostate cancer model

BackgroundProstate cancer (PCa) is the most prevalent cancer among males, emphasizing the critical need for precise diagnosis and treatment to enhance patient prognosis. Recent studies have extensively utilized urine exosomes from patients with cancer for targeted delivery. This study aimed to employ highly sensitive magnetic particle imaging (MPI) and fluorescence molecular imaging (FMI) to monitor the targeted delivery of an exosome-loaded platform at the tumour site, offering insights into a potential combined photothermal and magnetic thermal therapy regime for PCa.ResultsMPI and FMI were utilized to monitor the in vivo retention performance of exosomes in a prostate tumour mouse model. The exosome-loaded platform exhibited robust homologous targeting ability during imaging (SPIONs@EXO-Dye:66·48%±3·85%; Dye-SPIONs: 34·57%±7·55%, **P<0·01), as verified by in vitro imaging and in vitro tissue Prussian blue staining.ConclusionsThe experimental data underscore the feasibility of using MPI for in vivo PCa imaging. Furthermore, the exosome-loaded platform may contribute to the precise diagnosis and treatment of PCa.Graphical

Establishing mechanisms for nonlinear collector tribodynamics of magnetization under ferroresonance regimes

The paper considers a parallel electromagnetic oscillating circuit with a nonlinear inductance under conditions of excitation of ferroresonances. Physical mechanisms of dynamic self-regulation of the system of spin magnetic moments of ferromagnetic and ferrimagnetic dielectrics in the surrounding magnetic field are established. It is shown that upon entering the magnetic saturation regime, the effect of dynamic antiferroresonance is observed, due to the cyclic reversal of magnetization in the internal magnetic field. This effect has a collector character and corresponds to the maximum potential energy of the magnetic moment in the field and the antiparallel orientation of the moment with respect to the field. Such regimes are realized in thermodynamically non-equilibrium conditions and are correlated with unstable equilibrium positions of the corresponding mechanical analogues. The resulting forms of oscillations correlate with the dynamics of an inverted pendulum and have a significantly non-harmonic character. Autosynchronization of frequencies and nonlinear mixing of such forms with quasi-static modes imitating the time form of external excitation of oscillations were revealed. It is shown that the nonlinearity of ferromagnetic elements self-limits the height of resonance maxima. And on the other hand, it contributes to the cascade transport of energy by the spectrum of disturbances, which can have negative consequences when exciting low-frequency ferroresonances in power grids. The effect of dynamic antiferroresonance has the opposite direction to the known quasi-static behavior of the system of spin magnetic moments in an external field and must be taken into account when calculating and operating electrical systems with nonlinear inductances. Examples of collector self-oscillating modes similar in their physical mechanisms in nonlinear contact tribodynamics systems are given

Hidden transport phenomena in an ultraclean correlated metal

Advancements in materials synthesis have been key to unveil the quantum nature of electronic properties in solids by providing experimental reference points for a correct theoretical description. Here, we report hidden transport phenomena emerging in the ultraclean limit of the archetypical correlated electron system SrVO3. The low temperature, low magnetic field transport was found to be dominated by anisotropic scattering, whereas, at high temperature, we find a yet undiscovered phase that exhibits clear deviations from the expected Landau Fermi liquid, which is reminiscent of strange-metal physics in materials on the verge of a Mott transition. Further, the high sample purity enabled accessing the high magnetic field transport regime at low temperature, which revealed an anomalously high Hall coefficient. Taken with the strong anisotropic scattering, this presents a more complex picture of SrVO3 that deviates from a simple Landau Fermi liquid. These hidden transport anomalies observed in the ultraclean limit prompt a theoretical reexamination of this canonical correlated electron system beyond the Landau Fermi liquid paradigm, and more generally serves as an experimental basis to refine theoretical methods to capture such nontrivial experimental consequences emerging in correlated electron systems.

Multilayer Metamaterials with Ferromagnetic Domains Separated by Antiferromagnetic Domain Walls

AbstractMagnetic nano‐objects possess great potential for more efficient data processing, storage, and neuromorphic‐type applications. Using high perpendicular magnetic anisotropy synthetic antiferromagnets in the form of multilayer‐based metamaterials, the antiferromagnetic interlayer exchange energy is purposefully reduced below the out‐of‐plane demagnetization energy, which controls magnetic domain formation. In this unusual magnetic energy regime, as demonstrated via macroscopic magnetometry and microscopic Lorentz transmission electron microscopy, it becomes possible to stabilize nanometer‐scale stripe and bubble textures consisting of ferromagnetic out‐of‐plane domain cores separated by antiferromagnetic in‐plane Bloch‐type domain walls. This unique coexistence of mixed ferromagnetic/antiferromagnetic order on the nanometer scale opens so far unexplored perspectives in the architecture of magnetic domain landscapes as well as the design and functionality of individual magnetic textures, such as bubble domains with depth‐wise alternating chirality.

Design and Test of a Klystron Intra-Pulse Phase Feedback System for Electron Linear Accelerators

Beam stability and timing jitter in modern linear accelerators are becoming increasingly important. In particular, if a magnetic or radio-frequency (RF) compression regime is employed, the beam time of arrival jitter at the end of the linac can be strictly correlated with the phase noise of the accelerating fields of the RF structure working off-crest. For this reason, since 2008, an RF fast-feedback technique, which acts within each RF pulse, has been successfully employed at LNF-INFN (Laboratori Nazionali di Frascati dell’Istituto Nazionale di Fisica Nucleare) in the SPARC_LAB (Sources for Plasma Accelerators and Radiation Compton with Laser And Beam) facility on S-band (2856 MHz) klystrons powered by pulse-forming network (PFN) modulators, as reported in this paper. However, in order to meet the more stringent requirements of plasma wakefield acceleration schemes, some upgrades to this feedback system have been recently carried out. The first prototype has been experimentally tested on a C-band (5712 MHz) klystron, driven by a solid-state modulator, in order to investigate the possibility for additional improvement resulting from the inherently more stable power source. In this paper, the design, realization and the preliminary measurement results obtained at SPARC_LAB after such upgrades will be reviewed.

Observation of topological hall effect and skyrmions in Pt/Co/Ir/Co/Pt system

Abstract The interlayer exchange coupling (IEC) between two ferromagnetic (FM) layers separated by a non-magnetic (NM) spacer layer gives rise to different types of coupling with the variation of spacer layer thickness. When the NM is metallic, the IEC is attributed to the well-known Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction which shows an oscillatory decaying nature with increasing thickness. Due to this, it is possible to tune the coupling between the two FM to be either ferromagnetic or antiferromagnetic. In this work we have studied a Pt/Co/Ir/Co/Pt system where the Co thickness has been taken in the strong perpendicular magnetic anisotropy regime which is much less than the spin reorientation transition thickness. By tuning the Ir thickness to 2.0 nm, a canted state of magnetization reversal in the system is observed which gives rise to a possibility of nucleating topologically non-trivial spin textures like skyrmions. Further, with the combination of transport and magnetic force microscopy (MFM) measurements, we have confirmed the presence of skyrmions in our system. These findings may be useful for potential applications in emerging spintronic and data storage technologies using skyrmions.

The effect of pressure-anisotropy-driven kinetic instabilities on magnetic field amplification in galaxy clusters

Context. The intracluster medium (ICM) is the low-density diffuse gas that fills the space between galaxies within galaxy clusters. It is primarily composed of magnetized plasma, which reaches virial temperatures of up to 108 K, probably due to mergers of subhalos. Under these conditions, the plasma is weakly collisional and therefore has an anisotropic pressure tensor with respect to the local direction of the magnetic field. This triggers very fast, Larmor-scale, pressure-anisotropy-driven kinetic instabilities that alter magnetic field amplification. Aims. We aim to study magnetic field amplification through a turbulent, small-scale dynamo, including the effects of the kinetic instabilities, during the evolution of a typical massive galaxy cluster. A specific aim of this work is to establish a redshift limit from which a dynamo has to start to amplify the magnetic field up to equipartition with the turbulent velocity field at redshift z = 0. Methods. We implemented one-dimensional radial profiles for various plasma quantities for merger trees generated with the modified GALFORM algorithm. We assumed that turbulence is driven by successive mergers of dark matter halos and constructed effective models for the Reynolds number Reeff dependence on the magnetic field in three different magnetization regimes (unmagnetized, magnetized “kinetic”, and magnetized “fluid”), including the effects of kinetic instabilities. The magnetic field growth rate is calculated for the different Reeff models. Results. The model results in a higher magnetic field growth rate at higher redshift. For all scenarios considered in this study, to reach equipartition at z = 0, it is sufficient for the amplification of the magnetic field to start at redshift zstart ≈ 1.5 and above. The time to reach equipartition can be significantly shorter in cases with systematically smaller turbulent forcing scales and for the highest Reeff models. Conclusions. The origin of magnetic fields in the weakly collisional ICM can be explained by the small-scale turbulent dynamo, provided that the dynamo process starts beyond a given redshift. Merger trees are useful tools for studying the evolution of magnetic fields in weakly collisional plasmas, and could also be used to constrain the different stages of the dynamo that could potentially be observed by future radio telescopes.

Magnetotransport and Fermi surface segmentation in Pauli limited superconductors

We report the first theoretical investigation of the spectroscopic, electrical and optical transport signatures of d-wave Pauli limited superconductors, based on a non perturbative numerical approach. We demonstrate that the high magnetic field low temperature regime of these materials host a finite momentum paired superconducting phase. Multi-branched dispersion spectra with finite energy superconducting gaps, anisotropic segmentation of the Fermi surface and spatial modulations of the superconducting order characterizes this finite momentum paired phase and should be readily accessible through angle resolved photo emission spectroscopy, quasiparticle interference and differential conductance measurements. Based on the electrical and optical transport properties we capture the non Fermi liquid behavior of these systems at high temperatures, dominated by local superconducting correlations and characterized by resilient quasiparticles which survive the breakdown of the Fermi liquid description. We map out the generic thermal phase diagram of the d-wave Pauli limited superconductors and provide for the first time the accurate estimates of the thermal scales corresponding to the: (a) loss of (quasi) long range superconducting phase coherence (T c), (b) loss of local pair correlations (T pg), (c) breakdown of the Fermi liquid theory (T max) and cross-over from the non Fermi liquid to the bad metallic phase (T BR). Our thermal phase diagram mapped out on the basis of the spectroscopic and transport properties are found to be in qualitative agreement with the experimental observations on CeCoIn5 and κ-BEDT, in terms of the thermodynamic phases and the phase transitions. The results presented in this paper are expected to initiate important transport and spectroscopic experiments on the Pauli limited d-wave superconductors, providing sharp signatures of the finite momentum Cooper paired state in these materials.

Preparation of Fe@Fe3O4/ZnFe2O4 Powders and Their Consolidation via Hybrid Cold-Sintering/Spark Plasma-Sintering.

Our study is focused on optimizing the synthesis conditions for the in situ oxidation of Fe particles to produce Fe@Fe3O4 core-shell powder and preparation via co-precipitation of ZnFe2O4 nanoparticles to produce Fe@Fe3O4/ZnFe2O4 soft magnetic composites (SMC) through a hybrid cold-sintering/spark plasma-sintering technique. XRD and FTIR measurements confirmed the formation of a nanocrystalline oxide layer on the surface of Fe powder and the nanosized nature of ZnFe2O4 nanoparticles. SEM-EDX investigations revealed that the oxidic phase of our composite was distributed on the surface of the Fe particles, forming a quasi-continuous matrix. The DC magnetic characteristics of the composite compact revealed a saturation induction of 0.8 T, coercivity of 590 A/m, and maximum relative permeability of 156. AC magnetic characterization indicated that for frequencies higher than 1 kHz and induction of 0.1 T, interparticle eddy current losses dominated due to ineffective electrical insulation between neighboring particles in the composite compact. Nevertheless, the magnetic characteristics obtained in both DC and AC magnetization regimes were comparable to those reported for cold-sintered Fe-based SMCs.

Extending homogeneous fluidization flow regime of Geldart-A particles by exerting axial uniform and steady magnetic field

The homogeneous/particulate fluidization flow regime is particularly suitable for handling the various gas–solid contact processes encountered in the chemical and energy industry. This work aimed to extend such a regime of Geldart-A particles by exerting the axial uniform and steady magnetic field. Under the action of the magnetic field, the overall homogeneous fluidization regime of Geldart-A magnetizable particles became composed of two parts: inherent homogeneous fluidization and newly-created magnetic stabilization. Since the former remained almost unchanged whereas the latter became broader as the magnetic field intensity increased, the overall homogeneous fluidization regime could be extended remarkably. As for Geldart-A nonmagnetizable particles, certain amount of magnetizable particles had to be premixed to transmit the magnetic stabilization. Among others, the mere addition of magnetizable particles could broaden the homogeneous fluidization regime. The added content of magnetizable particles had an optimal value with smaller/lighter ones working better. The added magnetizable particles might raise the ratio between the interparticle force and the particle gravity. After the magnetic field was exerted, the homogeneous fluidization regime was further expanded due to the formation of magnetic stabilization flow regime. The more the added magnetizable particles, the better the magnetic performance and the broader the overall homogeneous fluidization regime. Smaller/lighter magnetizable particles were preferred to maximize the magnetic performance and extend the overall homogeneous fluidization regime. This phenomenon could be ascribed to that the added magnetizable particles themselves became more Geldart-A than -B type as their density or size decreased.

Magnetic Mode Coupling in Hyperbolic Bowtie Meta-Antennas.

Hyperbolic metaparticles have emerged as the next step in metamaterial applications, providing tunable electromagnetic properties on demand. However, coupling of optical modes in hyperbolic meta-antennas has not been explored. Here, we present in detail the magnetic and electric dipolar modes supported by a hyperbolic bowtie meta-antenna and clearly demonstrate the existence of two magnetic coupling regimes in such hyperbolic systems. The coupling nature is shown to depend on the interplay of the magnetic dipole moments, controlled by the meta-antenna effective permittivity and nanogap size. In parallel, the meta-antenna effective permittivity offers fine control over the electrical field spatial distribution. Our work highlights new coupling mechanisms between hyperbolic systems that have not been reported before, with a detailed study of the magnetic coupling nature, as a function of the structural parameters of the hyperbolic meta-antenna, which opens the route toward a range of applications from magnetic nanolight sources to chiral quantum optics and quantum interfaces.

Intermittent Theta Burst Stimulation Attenuates Cognitive Deficits and Alzheimer's Disease-Type Pathologies via ISCA1-Mediated Mitochondrial Modulation in APP/PS1 Mice.

Intermittent theta burst stimulation (iTBS), a time-saving and cost-effective repetitive transcranial magnetic stimulation regime, has been shown to improve cognition in patients with Alzheimer's disease (AD). However, the specific mechanism underlying iTBS-induced cognitive enhancement remains unknown. Previous studies suggested that mitochondrial functions are modulated by magnetic stimulation. Here, we showed that iTBS upregulates the expression of iron-sulfur cluster assembly 1 (ISCA1, an essential regulatory factor for mitochondrial respiration) in the brain of APP/PS1 mice. In vivo and in vitro studies revealed that iTBS modulates mitochondrial iron-sulfur cluster assembly to facilitate mitochondrial respiration and function, which is required for ISCA1. Moreover, iTBS rescues cognitive decline and attenuates AD-type pathologies in APP/PS1 mice. The present study uncovers a novel mechanism by which iTBS modulates mitochondrial respiration and function via ISCA1-mediated iron-sulfur cluster assembly to alleviate cognitive impairments and pathologies in AD. We provide the mechanistic target of iTBS that warrants its therapeutic potential for AD patients.

High-Cadence Observations of Magnetic Field Dynamics and Photospheric Emission Sources in the Eruptive Near-the-Limb X4.9 Solar Flare on 25 February, 2014: Evidences for Two-Stage Magnetic Reconnection during the Impulsive Phase

—We present an analysis of the pre-limb eruptive X4.9 solar flare on February 25, 2014, by means of which we confirm a hypothesis of the two-stage energy release corresponding to two magnetic reconnection regimes in the flare impulsive phase. This flare is selected, firstly, because of its morphological peculiarities suggesting the presence of the two energy release stages. Secondly, the flare was very suitably located near the solar limb and it was well-observed by many instruments. We performed an analysis of multiwavelength observational data of this flare region to find a connection between changes of the photospheric magnetic field, morphology of hard and soft X-ray sources, dynamics of the photospheric optical emission sources, metric radio bursts, and kinematics of an eruptive structure. The simultaneous usage of the line-of-sight and vector Helioseismic Magnetic Imager (HMI) magnetograms allowed us to trace magnetic field changes during the flare impulsive phase with high temporal resolution. HMI filtergrams allowed to trace displacement of the photospheric emission sources, associated with the magnetic reconnection, with very high temporal resolution up to 2 s. Using all observational results, we argue that the found flare stages are characterized by the following magnetic reconnection regimes. The first stage is predominantly characterized by the three-dimensional zipping reconnection in the strong sheared magnetic field assuming the tether-cutting geometry. The second stage corresponds to the so-called “standard” model of eruptive flares with the quasi-two-dimensional reconnection below the eruptive flux-rope. All observational peculiarities of these two stages are discussed in details.

Oblique dust-ion acoustic shock and oscillatory periodic wave excitations in space magnetized complex plasma regimes

The collisionless magnetized complex plasma (MCP) is considered to describe the nonlinear oblique propagation of dust-ion acoustic (DIA) shock wave and oscillatory wave having periodicity due to the impact of plasma parameters. Such plasma is composed of the dynamic ions having viscous influence, (α, q)-velocity distributed electrons, and static positive or negative dust charged particles. By implementing only the expansion of perturb quantities, the Burgers equation (BE) having quadratic nonlinearity (QN), cubic nonlinearity (CN), and composition of QN and CN are derived. Based on the useful exact solutions of these equations, the effect of physical parameters on the propagation of DIA shock wave, DIA oscillatory wave having periodicity and DIA double layer are discussed. It is found that the plasma system supports the shock and periodic wave excitations with both positive and negative polarity described by BE having QN. In addition, BE having CN supports shock and periodic wave excitations with only positive polarity. BE having a composition of QN and CN supports both shock wave excitations and double layer as well as both left to right and right to left propagating oscillatory waves having periodicity. The presented results would be applicable to space MCP regimes and further experimental verification.

Dynamical modes in a vertical nanocontact-based spin Hall nano-oscillator

Spin-torque nano-oscillators (STNOs) with high nonlinear tunability can serve as nanoscale spin-wave emitters for high-speed magnon-based logic circuits and neural networks for promising new energy-efficiency computing. Although various STNOs have been modeled theoretically and characterized experimentally, there is a sustained effort to improve their coherence and nonlinear tunability. By using numerical simulation, here we explore the evolution rule of spectral characteristics and nonlinearities of the emitted coherent spin waves in a type of spin Hall nano-oscillator (SHNO) with a perpendicular magnetic anisotropy (PMA) coefficient ${K}_{u}$, which is based on a vertical nanocontact fabricated on an extended heavy metal/ferromagnet bilayer. There exist three distinct dynamic regimes with varying ${K}_{u}$. At the easy-plane anisotropy-dominated in-plane magnetized regime, the SHNO exhibits coexistence of the nonlinear self-localized spin-wave bullet mode with a significantly negative nonlinearity coefficient $\ensuremath{\aleph}$ and a secondary high-frequency quasilinear edge mode at higher current density. The latter excitation is supported by the energy transfer from the former via nonlinear coupling rather than the injected spin currents located in the center nanogap of the device. When the easy-plane shape anisotropy is effectively compensated by PMA, only a single quasipropagating spin-wave mode with a near-zero $\ensuremath{\aleph}$ is excited at lower current density, consistent with minimization of nonlinear damping due to the suppression of nonlinear mode coupling. For the out-of-plane magnetized SHNOs with ${K}_{u}$ above the demagnetization energy, a well-defined propagating spin-wave mode with a positive $\ensuremath{\aleph}$, characterized by a significant frequency blueshift and a rightward elongated spatial profile perpendicular to the in-plane component of the applied magnetic field, is observed. This detailed evolution diagram of auto-oscillating dynamics on the PMA coefficient ${K}_{u}$ provides a practical approach to selectively excite dynamical modes and optimize the spectral characteristics of the SHNO for applications in microwave technology and spin-wave logic.

Magnetic Field Dynamical Regimes in a Large-Scale Low-Mode αΩ-Dynamo Model with Hereditary α-Quenching by Field Energy

The article considers a large-scale model of an αΩ-dynamo in the low-mode approximation. The intensity of the α-effect is regulated by a process that depends on the energy of the magnetic field and has hereditarity properties (finite “memory”). The regulation process is included in the MHD-system in the form of an additive correction. The action character of the process is defined by the alternating kernel with variable parameters: the damping frequency and the damping coefficient. The Reynolds number and the α-effect measure are the control parameters of the system. Information about the action of a large-scale generator is contained in the Reynolds number, and that about the action of a turbulent one is contained in the measure of the α-effect. The stability of the solution of the MHD-system is studied depending on the values of the control parameters and the parameters of the alternating kernel. Based on the results of numerical simulation of the dynamical regimes, limitations are determined for the values of the model parameters at which the regimes are reproduced against the background of small oscillations of the viscous liquid velocity field. The results of the study of the stability of solutions and numerical simulations of the dynamical regimes are represented on the phase plane of the control parameters. The paper investigates the question of changing the pattern on the phase plane depending on the values of the damping coefficient, the damping frequency, and the waiting time. A comparison is made with the results obtained earlier, when the α-effect intensity is a constant or is regulated by a process with an exponential kernel and the same values of the damping coefficient.

Magnetic functionalization of ZnO nanoparticles surfaces via optically generated methyl radicals.

The combination of nuclear and electron magnetic resonance techniques, in pulse and continuous wave regimes, is used to unravel the nature and features of the light-induced magnetic state arising at the surface of chemically prepared zinc oxide nanoparticles (NPs) occurring under 120K when subjected to a sub-bandgap (405nm) laser excitation. It is shown that the four-line structure observed around g ∼ 2.00 in the as-grown samples (beside the usual core-defect signal at g ∼ 1.96) arises from surface-located methyl radicals (•CH3), originating from the acetate capped ZnO molecules. By functionalizing the as-grown zinc oxide NPs with deuterated sodium acetate, the •CH3 electron paramagnetic resonance (EPR) signal is replaced by trideuteromethyl (•CD3). For •CH3, •CD3, and core-defect signals, an electron spin echo is detected below ∼100K, allowing for the spin-lattice and spin-spin relaxation-time measurements for each of them. Advanced pulse-EPR techniques reveal the proton or deuteron spin-echo modulation for both radicals and give access to small unresolved superhyperfine couplings between adjacent •CH3. In addition, electron double resonance techniques show that some correlations exist between the different EPR transitions of •CH3. These correlations are discussed as possibly arising from cross-relaxation phenomena between different rotational states of radicals.

Suppression of the Equivalent Magnetic Noise Caused by Electron Spin Polarization in a Xe Isotope Comagnetometer

The Xe isotope comagnetometer in the nuclear magnetic resonance regime can be used as a promising high-precision inertial measurement unit because of the absolute frequency measurement and high bandwidth. The fluctuation of the electron spin polarization leads to equivalent magnetic noise in the Xe isotope comagnetometer, which is one of the main factors limiting the stability of the comagnetometer. Here, we demonstrate systematic research of equivalent magnetic noise suppression and analyze the influence of the electron spin polarization on the Xe isotope comagnetometer. Based on the spin–exchange method between Xe isotopes and alkali metal atoms through the Fermi contact hyperfine interaction, the error equation of the Xe Larmor frequency is established. The equivalent magnetic noise can be suppressed by controlling the static magnetic field. This suppression method for Xe isotope comagnetometers improved the stability while maintaining high bandwidth. The experimental results show that this method can reduce the fluctuations of the 129Xe and 131Xe frequencies by 75% and 68.6%, respectively.

A comparative thermal case study on thermophysical aspects in thermally magnetized flow regime with variable thermal conductivity

It is well consensus among researchers affiliated with the field of thermal engineering that the thermophysical characteristics of heat transfer in fluid science own abundant applications like thermal distillation systems, heat exchangers, steam-electric power generation, electronic cooling, solar collectors, refrigeration systems and spacecraft thermal protection are to mention just a few. Considering such importance we offer a thermal case study on thermophysical aspects in a thermally magnetized non-Newtonian fluid along with a first-order chemical reaction effect. The flow field is carried with the following thermophysical effects namely, mixed convection, heat generation, viscous dissipation, thermal radiations, and temperature-dependent variable thermal conductivity. We have offered comparative analysis for temperature and Nusselt number by considering thermally radiative and non-radiative thermal flow fields. The thermal outcomes on temperature and Nusselt number are also reported for both the absence and presence of the heat generation effect. For both radiative and non-radiative Casson flow, the temperature shows an inciting nature towards Casson and variable thermal conductivity parameters. The magnitude of the Nusselt number towards Eckert, Prandt numbers, curvature, heat generation, and Casson fluid parameters is higher for the presence of thermal radiations while the opposite is the case for positive variation in the thermal conductivity parameter.