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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Search for spin-polarized photoemission from GaAs using light with orbital angular momentum
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Dy-V magnetic interaction and local structure bias on the complex spin and orbital ordering in Dy₁₋ x Tb x VO₃ (x=0 and 0.2)
The spin and orbital ordering in Dy₁₋ x Tb x VO₃ (x=0 and 0.2) was studied by measuring x-ray powder diffraction, magnetization, specific heat, and neutron single-crystal diffraction. The results show that G-OO/C-AF and C-OO/G-AF phases coexist in Dy 0.8 Tb 0.20 VO 3 in the temperature range 2–60 K, and the volume fraction of each phase is temperature and field dependent. The ordering of Dy moments at T* = 12 K induces a transition from G-OO/C-AF to a C-OO/G-AF phase. Magnetic fields suppress the long-range order of Dy moments and thus the C-OO/G-AF phase below T*. The polarized moments induced at the Dy sublattice by external magnetic fields couple to the V 3d moments, and this coupling favors the G-OO/C-AF state. Also discussed is the effect of the Dy-V magnetic interaction and local structure distortion on the spin and orbital ordering in Dy₁₋ x Tb x VO₃.
Orbital selective directional conductor in the two-orbital Hubbard model
Recently, we employed a developed many-body technique that allows for the incorporation of thermal effects, the rich phase diagram of a two-dimensional two-orbital (degenerate d xz and d yz ) Hubbard model is presented varying temperature and the repulsion U. The main result is the finding at intermediate U of an antiferromagnetic orbital selective state where an effective dimensional reduction renders one direction insulating and the other metallic. Possible realizations of this state are discussed. Additionally, we also study nematicity above the N eel temperature. After a careful finite-size scaling analysis, the nematicity temperature window appears to survive in the bulk limit, although it is very narrow.
Orbital superconductivity, defects, and pinned nematic fluctuations in the doped iron chalcogenide FeSe 0.45 Te 0.55
We demonstrate that the differential conductance, dI/dV , measured via spectroscopic imaging scanning tunneling microscopy in the doped iron chalcogenide FeSe 0.45 Te 0.55 , possesses a series of characteristic features that allow one to extract the orbital structure of the superconducting gaps. This yields nearly isotropic superconducting gaps on the two hole-like Fermi surfaces, and a strongly anisotropic gap on the electron-like Fermi surface. Moreover, we show that the pinning of nematic fluctuations by defects can give rise to a dumbbell-like spatial structure of the induced impurity bound states, and explains the related C 2 -symmetry in the Fourier transformed differential conductance.
Mott transition controlled by lattice-orbital coupling in 3 d -metal-doped double-layer ruthenates
We have investigated unusual phase transitions that were triggered by chemical doping in Ca 3 Ru 2 O 7 . Our experiments showed that doping with a few percent of Mn (>4%) can change the quasi-two-dimensional metallic state of Ca 3 Ru 2 O 7 into a Mott insulating state with a G-type antiferromagnetic order, but this Mott state cannot be induced by Fe doping. By combining these results with first-principles calculations, we show that lattice-orbital coupling (LOC) plays an important role in the Mott transition. Interestingly, the transition temperature T MIT is found to be predetermined by a structural parameter denoted by c/√ab at temperatures far above Néel temperature T N . This LOC-assisted Mott transition clearly contrasts with the band-filling picture. It is addressed that this type of Mott transition originates in the strong scattering centers formed by specific 3d dopants. The dopant-scattering picture is then applied to explain the puzzling doping effects that occur in other ruthenates and 3d oxides. As a result, our findings will advance the general understanding of how the unusual properties of 4d correlated systems are governed by the complex interplay that occurs among the charge, spin, lattice, and orbital degrees of freedom.
Exploring orbital angular momentum and spin-orbit correlations for gluons at the Electron-Ion Collider
In our previous work [S. Bhattacharya , ], we introduced a pioneering observable aimed at experimentally detecting the orbital angular momentum (OAM) of gluons. Our focus was on the longitudinal double spin asymmetry observed in exclusive dijet production during electron-proton scattering. We demonstrated the sensitivity of the cos ϕ angular correlation between the scattered electron and proton as a probe for gluon OAM at small x and its intricate interplay with gluon helicity. This current work provides a comprehensive exposition, diving further into the aforementioned calculation with added elaboration and in-depth analysis. We reveal that, in addition to the gluon OAM, one also gains access to the spin-orbit correlation of gluons. We supplement our work with a detailed numerical analysis of our observables for the kinematics of the Electron-Ion Collider. In addition to dijet production, we also consider the recently proposed semi-inclusive diffractive deep inelastic scattering process, which potentially offers experimental advantages over dijet measurements. Finally, we investigate quark-channel contributions to these processes and find an unexpected breakdown of collinear factorization. Published by the American Physical Society 2025
Asymmetric Orbital-Lattice Interactions in Ultrathin Correlated Oxide Films
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Tuning the Magnetic Exchange via a Control of Orbital Hybridization in Cr 2 ( Te 1 - x W x ) O 6
Here, we report the complex magnetic phase diagram and electronic structure of Cr 2 ( Te 1-x W x ) O 6 systems. While compounds with different x values possess the same crystal structure, they display different magnetic structures below and above x c = 0.7 , where both the transition temperature T N and sublattice magnetization (M s ) reach a minimum. Unlike many known cases where magnetic interactions are controlled either by injection of charge carriers or by structural distortion induced via chemical doping, in the present case it is achieved by tuning the orbital hybridization between Cr 3d and O 2p orbitals through W 5d states. The result is supported by ab initio electronic structure calculations. Through this concept, we introduce a new approach to tune magnetic and electronic properties via chemical doping.
Two-Dimensional Electron Gases at LaAlO 3 /SrTiO 3 Interfaces: Orbital Symmetry and Hierarchy Engineered by Crystal Orientation
Recent findings show the emergence of two-dimensional electron gases (2DEGs) at LaAlO 3 /SrTiO 3 interfaces along different orientations; yet details on band reconstructions have remained so far unknown. In this study, via x-ray linear dichroism spectroscopy, we demonstrate that crystal symmetry imposes distinctive 2DEG orbital hierarchies on (001)-and (110)-oriented quantum wells, allowing selective occupancy of states of different symmetry. Such orientational tuning expands the possibilities for electronic engineering of 2DEGs and opens up enticing opportunities to understand the link between orbital symmetry and complex correlated states at LaAlO 3 /SrTiO 3 quantum wells.
Slater Insulator in Iridate Perovskites with Strong Spin-Orbit Coupling
The perovskite (Pv) SrIrO 3 is an exotic narrow-band metal owing to a confluence of the strengths of the spin-orbit coupling (SOC) and the electron-electron correlations. It has been proposed that topological and magnetic insulating phases can be achieved by tuning the SOC, Hubbard interactions, and/or lattice symmetry. Here, we report that the substitution of nonmagnetic, isovalent Sn 4+ for Ir 4+ in the SrIr 1-x Sn x O 3 perovskites synthesized under high pressure leads to a metal-insulator transition to an antiferromagnetic phase at TN ≥ 225 K. The continuous change of the cell volume as detected by X-ray diffraction and the l-shape transition of the specific heat on cooling through TN demonstrate that the metal-insulator transition is of second-order. Neutron powder diffraction results indicate that the Sn substitution enlarges an octahedral-site distortion that reduces the SOC relative to the spin-spin exchange interaction and results in the type-G AF spin ordering below TN. Measurement of high-temperature magnetic susceptibility shows the evolution of magnetic coupling in the paramagnetic phase typical of weak itinerant-electron magnetism in the Sn-substituted samples. A reduced structural symmetry in the magnetically ordered phase leads to an electron gap opening at the Brillouin zone boundary below TN in the same way as proposed by Slater.
Novel Strongly Spin-Orbit Coupled Quantum Dimer Magnet: Yb[subscript 2]Si[subscript 2]O[subscript 7]
Abstract not provided
Generation of extreme-ultraviolet beams with time-varying orbital angular momentum
Light fields carrying orbital angular momentum (OAM) provide powerful capabilities for applications in optical communications, microscopy, quantum optics, and microparticle manipulation. We introduce a property of light beams, manifested as a temporal OAM variation along a pulse: the self-torque of light. Although self-torque is found in diverse physical systems (i.e., electrodynamics and general relativity), it was not realized that light could possess such a property. We demonstrate that extreme-ultraviolet self-torqued beams arise in high-harmonic generation driven by time-delayed pulses with different OAM. We monitor the self-torque of extreme-ultraviolet beams through their azimuthal frequency chirp. Lastly, this class of dynamic-OAM beams provides the ability for controlling magnetic, topological, and quantum excitations and for manipulating molecules and nanostructures on their natural time and length scales.
Data for vehicle design for earth orbit to mars orbit and return.
Payload and speed requirements of an earth orbit to mars orbit and return manned spacecraft, using a nuclear heat exchanger-type propulsion system
The orbiting astronomical observatory and the orbiting solar observatory
Orbiting Solar Observatory and Orbiting Astronomical Observatory
Two-center problem orbits as intermediate orbits for the restricted three-body problem
Two-center problem orbit as intermediate orbit for restricted three-body problem