Thermal and magnetoelastic properties of α-RuCL3 in the field induced low temperature states
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High Magnetic Field Science↗
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Magnetic field stabilized electron-hole liquid in indirect-band-gap A l x G a 1 - x As
An electron-hole liquid (EHL), a condensed liquidlike phase of free electrons and holes in a semiconductor, presents a unique system for exploring quantum many-body phenomena. And while the behavior of EHLs is generally understood, less attention has been devoted to systematically varying the onset of their formation and resulting properties. Here, we report on an experimental approach to tune the conditions of formation and characteristics using a combination of low excitation densities and high magnetic fields up to 90 T. Demonstration of this approach was carried out in indirect-band-gap A l 0.387 G a 0.613 As . EHL droplets can be nucleated from one of two multiexciton complex states depending on the applied excitation density. Furthermore, the excitation density influences the carrier density of the EHL at high magnetic fields, where filling of successive Landau levels can be controlled. The ability to manipulate the formation pathway, temperature, and carrier density of the EHL phase under otherwise fixed experimental conditions makes our approach a powerful tool for studying condensed carrier phases in further detail.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Exchange field effect in the crystal-field ground state of Ce M Al 4 Si 2
The crystal-field ground-state wave functions of the tetragonal, magnetically ordering Kondo lattice materials CeMAl 4 Si 2 (M = Rh, Ir, and Pt) are determined in this paper with low-temperature linearly polarized soft-x-ray absorption spectroscopy, and estimates for the crystal-field splittings are given from the temperature evolution of the linear dichroism. Values for the dominant exchange field in the magnetically ordered phases can be obtained from fitting the influence of magnetic order on the linear dichroism. The direction of the required exchange field is || c for the antiferromagnetic Rh and Ir compounds, with the corresponding strength of the order of λ ex ≈ 6 meV (65 K). Finally and furthermore, the presence of Kondo screening in the Rh and Ir compound is demonstrated on the basis of the absorption due to f 0 in the initial state.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Magnetic phase diagram and electronic structure of UPt 2 Si 2 at high magnetic fields: A possible field-induced Lifshitz transition
We have measured Hall effect, magnetotransport and magnetostriction on the field induced phases of single crystalline UPt2Si2 in magnetic fields up to 60T at temperatures down to 50mK, this way firmly establishing the phase diagram for magnetic fields Bka and c axes. Moreover, for Bkc axis we observe strong changes in the Hall effect at the phase boundaries. From a comparison to band structure calculations utilizing the concept of a dual nature of the uranium 5f electrons, we propose that these represent field induced topological changes of the Fermi surface due to at least one Lifshitz transition. Furthermore, we find a unique history dependence of the magnetotransport and magnetostriction data, indicating that the proposed Lifshitz type transition is of a discontinuous nature, as predicted for interacting electron systems.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Simultaneous scanning near-field optical and X-ray diffraction microscopy for correlative nanoscale structure-property characterization
A multimodal imaging instrument has been developed that integrates scanning near-field optical microscopy with nanofocused synchrotron X-ray diffraction imaging. The instrument allows for the simultaneous nanoscale characterization of electronic/near-field optical properties of materials together with their crystallographic structure, facilitating the investigation of local structure–property relationships. The design, implementation and operating procedures of this instrument are reported. The scientific capabilities are demonstrated in a proof-of-principle study of the insulator–metal phase transition in samarium sulfide (SmS) single crystals induced by applying mechanical pressure via a scanning tip. The multimodal imaging of an in situ tip-written region shows that the near-field optical reflectivity can be correlated with the heterogeneously transformed structure of the near-surface region of the crystal.
insulator–metal transitions↗
Field Quality of the First LARP Nb3Sn 3.7 m-Long Quadrupole Model of LQ Series
The US-LHC accelerator research program (LARP) built and tested the first 3.7-m long Nb{sub 3}Sn quadrupole model of LQ series with a 90 mm bore diameter and a target field gradient of 200 T/m. The LQ series, developed in collaboration among FNAL, LBNL and BNL, is a scale up of the previously tested 1-m long technology quadrupoles of TQ series based on similar coils and two different mechanical structures (shell-based TQS and collar-based TQC), with a primary goal of demonstrating the Nb{sub 3}Sn accelerator magnet technology for the luminosity upgrade of LHC interaction regions. In this paper, we present the field quality measurements in the first 3.7-m long LQS01 model based on the modified TQS mechanical structure. The results are compared to the expectations from the magnet geometry and magnetic properties of coils and iron yoke. Moreover, we present a comparison between this magnet and the short models previously measured.
43 PARTICLE ACCELERATORS↗
A Comparison of Radiation-Induced and High-Field Electrically Stress-Induced Interface Defects in Si/SiO 2 MOSFETs via Electrically Detected Magnetic Resonance
Here, we utilize electrically detected magnetic resonance (EDMR) measurements to compare high-field stressed, and gamma irradiated Si/SiO 2 metal–oxide–silicon (MOS) structures. We utilize spin-dependent recombination (SDR) EDMR detected using the Fitzgerald and Grove dc I-V approach to compare the effects of high-field electrical stressing and gamma irradiation on defect formation at and near the Si/SiO 2 interface. As anticipated, both greatly increase the concentration of P b centers (silicon dangling bonds at the interface) densities. The irradiation also generated a significant increase in the dc I-V EDMR response of E' centers (oxygen vacancies in the SiO 2 films), whereas the generation of an E' EDMR response in high-field stressing is much weaker than in the gamma irradiation case. These results likely suggest a difference in their physical distribution resulting from radiation damage and high electric field stressing.
42 ENGINEERING↗
Scalar Field Comparison with Topological Descriptors: Properties and Applications for Scientific Visualization
In topological data analysis and visualization, topological descriptors such as persistence diagrams, merge trees, contour trees, Reeb graphs, and Morse–Smale complexes play an essential role in capturing the shape of scalar field data. Herein we present a state–of–the–art report on scalar field comparison using topological descriptors. We provide a taxonomy of existing approaches based on visualization tasks associated with three categories of data: single fields, time–varying fields, and ensembles. These tasks include symmetry detection, periodicity detection, key event/feature detection, feature tracking, clustering, and structure statistics. Our main contributions include the formulation of a set of desirable mathematical and computational properties of comparative measures, and the classification of visualization tasks and applications that are enabled by these measures.
97 MATHEMATICS AND COMPUTING↗
Field Soil Water Retention of the Prototype Hanford Barrier and Its Variability with Space and Time
Engineered surface barriers (or covers) are used to isolate underlying contaminants from water, plants, animals, and humans. To understand the flow processes within a barrier and the barrier's ability to store and release water, the field hydraulic properties of the barrier need to be known. A multiyear test of the evapotranspiration (ET) barrier at the US Department of Energy's Hanford Site in the southeast of the state of Washington has yielded in situ soil water content and pressure data from multiple locations for a 9‐yr period, offering the opportunity to estimate soil water retention properties at different locations and times. The upper 2‐m layer of the ET barrier is a silt loam, and the top 1 m also contains 15% (w/w) pea gravel. Within this layer, valid monitoring data from 1995 to 2003 for four depths at 12 monitoring stations were used to determine the field water retention of the silt loam, with and without gravel. The data covered a wide range of wetness, from near saturation to the permanent wilting point, and each retention curve contained 51 to 96 data points. The data were described well with the commonly used van Genuchten water retention model. It was found that the spatial variation of the saturated and residual water content and the pore size distribution parameter was relatively small, while that of the van Genuchten α was relatively large. The effects of spatial variability of the retention properties appeared to be larger than the combined effects of added pea gravel and plant roots on the properties. Neither the primary wetting process in the winter season nor the drying process in the summer season nor time had a detectable effect on the water retention of the silt loam barrier.
Zhang, Z. Fred↗
Algorithms for Computing the Magnetic Field, Vector Potential, and Field Derivatives for a Thin Solenoid with Uniform Current Density
A numerical algorithm for computing the field components B r and B z and their r and z derivatives with open boundaries in cylindrical coordinates for radially thin solenoids with uniform current density is described in this note. An algorithm for computing the vector potential A θ is also described. For the convenience of the reader, derivations of the final expressions from their defining integrals are given in detail, since their derivations are not all easily found in textbooks. Numerical calculations are based on evaluation of complete elliptic integrals using the Bulirsch algorithm cel. The (apparently) new feature of the algorithms described in this note applies to cases where the field point is outside of the bore of the solenoid and the field-point radius approaches the solenoid radius. Since the elliptic integrals of the third kind normally used in computing B z and A θ become infinite in this region of parameter space, fields for points with the axial coordinate z outside of the ends of the solenoid and near the solenoid radius are treated by use of elliptic integrals of the third kind of modified argument, derived by use of an addition theorem. Also, the algorithms also avoid the numerical difficulties the textbook solutions have for points near the axis arising from explicit factors of 1/r or 1/r 2 in the some of the expressions.
97 MATHEMATICS AND COMPUTING↗
POLARIZATION SIGNATURES OF RELATIVISTIC MAGNETOHYDRODYNAMIC SHOCKS IN THE BLAZAR EMISSION REGION. I. FORCE-FREE HELICAL MAGNETIC FIELDS
The optical radiation and polarization signatures in blazars are known to be highly variable during flaring activities. It is frequently argued that shocks are the main driver of the flaring events. However, the spectral variability modelings generally lack detailed considerations of the self-consistent magnetic field evolution modeling; thus, so far the associated optical polarization signatures are poorly understood. We present the first simultaneous modeling of the optical radiation and polarization signatures based on 3D magnetohydrodynamic simulations of relativistic shocks in the blazar emission environment, with the simplest physical assumptions. By comparing the results with observations, we find that shocks in a weakly magnetized environment will largely lead to significant changes in the optical polarization signatures, which are seldom seen in observations. Hence an emission region with relatively strong magnetization is preferred. In such an environment, slow shocks may produce minor flares with either erratic polarization fluctuations or considerable polarization variations, depending on the parameters; fast shocks can produce major flares with smooth polarization angle rotations. In addition, the magnetic fields in both cases are observed to actively revert to the original topology after the shocks. All these features are consistent with observations. Future observations of the radiation and polarization signatures will further constrain the flaring mechanism and the blazar emission environment.
79 ASTRONOMY AND ASTROPHYSICS↗
Nonlinear Transverse Cascade and Sustenance of MRI Turbulence in Keplerian Disks with an Azimuthal Magnetic Field
We investigate magnetohydrodynamic turbulence driven by the magnetorotational instability (MRI) in Keplerian disks with a nonzero net azimuthal magnetic field using shearing box simulations. As distinct from previous studies, we analyze turbulence dynamics in Fourier (k-) space to understand its sustenance. The linear growth of the MRI with the azimuthal field has a transient character and is anisotropic in Fourier space, leading to anisotropy of nonlinear processes in Fourier space. As a result, the main nonlinear process appears to be a new type of angular redistribution of modes in Fourier space—the nonlinear transverse cascade—rather than the usual direct/inverse cascade. We demonstrate that the turbulence is sustained by the interplay of the linear transient growth of the MRI (which is the only energy supply for the turbulence) and the transverse cascade. These two processes operate at large length scales, comparable to the box size (disk scale height); the corresponding small wavenumber area, called the vital area in Fourier space, is crucial for the sustenance, while outside the vital area, direct cascade dominates. The interplay of the linear and nonlinear processes in Fourier space is generally too intertwined for a vivid schematization. Nevertheless, we reveal the basic subcycle of the sustenance that clearly shows the synergy of these processes in the self-organization of the magnetized flow system. This synergy is quite robust and persists for the considered different aspect ratios of the simulation boxes. The spectral characteristics of the dynamical processes in these boxes are qualitatively similar, indicating the universality of the sustenance mechanism of the MRI turbulence.
79 ASTRONOMY AND ASTROPHYSICS↗
Distortion of Magnetic Fields in a Starless Core II: 3D Magnetic Field Structure of FeSt 1-457
Three-dimensional (3D) magnetic field information on molecular clouds and cores is important for revealing their kinematical stability (magnetic support) against gravity, which is fundamental for studying the initial conditions of star formation. In the present study, the 3D magnetic field structure of the dense starless core FeSt 1-457 is determined based on the near-infrared polarimetric observations of the dichroic polarization of background stars and simple 3D modeling. With an obtained angle of line-of-sight magnetic inclination axis θ{sub inc} of 45{sup ∘}±10{sup ∘} and previously determined plane-of-sky magnetic field strength B{sub pol} of 23.8 ± 12.1 μG, the total magnetic field strength for FeSt 1-457 is derived to be 33.7 ± 18.0 μG. The critical mass of FeSt 1-457, evaluated using both magnetic and thermal/turbulent support is M{sub cr}=3.70±0.92 M{sub ⊙}, which is identical to the observed core mass, M{sub core}=3.55±0.75 M{sub ⊙}. We thus conclude that the stability of FeSt 1-457 is in a condition close to the critical state. Without infalling gas motion and no associated young stars, the core is regarded to be in the earliest stage of star formation, i.e., the stage just before the onset of dynamical collapse following the attainment of a supercritical condition. These properties could make FeSt 1-457 one of the best starless cores for future studies of the initial conditions of star formation.
79 ASTRONOMY AND ASTROPHYSICS↗
Clear Lake Volcanic Field Disasters: Creating a Deformation Record Using InSAR to Assess Hazards and Detect Volcanic Unrest in Clear Lake Volcanic Field
Clear Lake Volcanic Field (CLVF) in northern California is at a high threat potential for volcanic hazards. Eruptions leading to increased seismic activity could result in silicic domes, cinder cones, and flows that would be dangerous to the residential areas near the volcanic field. Remotely sensed Earth observations can reveal volcanic processes in the subsurface, which are essential to the timely monitoring of potential volcanic activity. In particular, Sentinel-1 C-band Synthetic Aperture Radar (C-SAR) and Digital Elevation Model (DEM) data capture relative surface deformation at unprecedented high spatial and temporal resolutions. Leveraging C-SAR and DEMs, we conducted interferometric analysis from January 2016 to December 2023. Our results demonstrate 1) the mean surface displacement velocity of the Clear Lake Volcanic Field is measured to undergo 5 to 10-centimeter scale deformation and shows a strong relationship with the surrounding faults, 2) apparent seasonal differences in rates of surface change, and 3) seismic activity associated with the geyser geothermal field has a strong association with cumulative surface displacement, with active fault zones having 2 to 5 cm of additional displacement. Results indicate that deformation is linked to deep pressure sources causing stresses on the surficial environment that should be considered in hazard mitigation. This study provides a baseline of historic deformation, aiding hazard analysts in communication efforts and streamlining decision-making for potential risks to region residents.
remote sensing↗
Field redefinitions and infinite field anomalous dimensions
Field redefinitions are commonly used to reduce the number of operators in the Lagrangian by removing redundant operators and transforming to a minimal operator basis. We give a general argument that such field redefinitions, while leaving the S-matrix invariant and consequently finite, lead not only to infinite Green’s functions, but also to infinite field anomalous dimensions γ ϕ . These divergences cannot be removed by counterterms without reintroducing redundant operators.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Random Crystal Field Effect on the Kinetic Spin-1 and Spin-3/2 Under a Time-Dependent Oscillating Field Phase Transitions
The effect of random crystal field on the stationary states of the kinetic spin-1 and spin-3/2 Blume-Capel model is investigated within the framework of the mean field approach. The Glauber-type stochastic dynamics is used to describe the time evolution of the system which is subjected to a time-dependent oscillating external magnetic field. The model exhibits first- and second-order transitions as well as dynamical tricritical, triple and an isolated critical end points. We found that the system displays reentrant phenomenon for both α = 0 and α > 0. Moreover, the system exhibits in the phase space a fixed points and limit cycles with circle, elliptic and parallelogram shapes.
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
Quantum ${{\mathbb{F}}_{{\rm un}}}$: the q = 1 limit of Galois field quantum mechanics, projective geometry and the field with one element
We argue here that the q = 1 limit of Galois field quantum mechanics, which was constructed on a vector space over the Galois field ${{\mathbb{F}}_{q}}=GF(q)$, corresponds to its 'classical limit', where superposition of states is disallowed. Furthermore, the limit preserves the projective geometry nature of the state space, and can be understood as being constructed on an appropriately defined analogue of a 'vector' space over the 'field with one element' ${{\mathbb{F}}_{1}}$.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗