Verification of Photometric Parallaxes with Gaia DR2 Data

Results of comparison of Gaia DR2 parallaxes with data derived from a combined analysis of 2MASS (Two Micron All-Sky Survey), SDSS (Sloan Digital Sky Survey), GALEX (Galaxy Evolution Explorer), and UKIDSS (UKIRT Infrared Deep Sky Survey) surveys in four selected high-latitude $|b|>48^{\circ}$ sky areas are presented. It is shown that multicolor photometric data from large modern surveys can be used for parameterization of stars closer than 4400 pc and brighter than $g_{SDSS} = 19.^m6$, including estimation of parallax and interstellar extinction value. However, the stellar luminosity class should be properly determined.Comment: 11 pages, 5 figure

Variation of the character of spin-orbit interaction by Pt intercalation underneath graphene on Ir(111)

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).-- et al.The modification of the graphene spin structure is of interest for novel possibilities of application of graphene in spintronics. The most exciting of them demand not only high value of spin-orbit splitting of the graphene states, but non-Rashba behavior of the splitting and spatial modulation of the spin-orbit interaction. In this work we study the spin and electronic structure of graphene on Ir(111) with intercalated Pt monolayer. Pt interlayer does not change the 9.3×9.3 superlattice of graphene, while the spin structure of the Dirac cone becomes modified. It is shown that the Rashba splitting of the π state is reduced, while hybridization of the graphene and substrate states leads to a spin-dependent avoided-crossing effect near the Fermi level. Such a variation of spin-orbit interaction combined with the superlattice effects can induce a topological phase in graphene.The work was partially supported by grants of Saint Petersburg State University for scientific investigations (Grants No. 11.38.271.2014, No. 15.61.202.2015 and No. 11.37.634.2013) and Russian Foundation for Basic Research (RFBR) projects (No. 13-02-91327). We acknowledge the financial support of the University of Basque Country UPV/EHU (Grant No. GIC07-IT-756-13), the Departamento de Educacion del Gobierno Vasco, and the Spanish Ministerio de Ciencia e Innovacion (Grant No. FIS2010-19609-C02-01), the Spanish Ministry of Economy and Competitiveness MINECO (Grant No. FIS2013-48286-C2-1-P), and the Tomsk State University Competitiveness Improvement Program.Peer Reviewe

Variation of the character of spin-orbit interaction by Pt intercalation underneath graphene on Ir(111)

The modification of the graphene spin structure is of interest for novel possibilities of application of graphene in spintronics. The most exciting of them demand not only high value of spin-orbit splitting of the graphene states, but non-Rashba behavior of the splitting and spatial modulation of the spin-orbit interaction. In this work we study the spin and electronic structure of graphene on Ir(111) with intercalated Pt monolayer. Pt interlayer does not change the 9.3×9.3 superlattice of graphene, while the spin structure of the Dirac cone becomes modified. It is shown that the Rashba splitting of the π state is reduced, while hybridization of the graphene and substrate states leads to a spin-dependent avoided-crossing effect near the Fermi level. Such a variation of spin-orbit interaction combined with the superlattice effects can induce a topological phase in graphene

Classical and cubic Rashba effect in the presence of in-plane 4f magnetism at the iridium silicide surface of the antiferromagnet GdIr2Si2

We present a combined experimental and theoretical study of the two-dimensional electron states at the iridium-silicide surface of the antiferromagnet GdIr2Si2 above and below the Ned temperature. Using angle-resolved photoemission spectroscopy (ARPES) we find a significant spin-orbit splitting of the surface states in the paramagnetic phase. By means of ab initio density-functional-theory (DFT) calculations we establish that the surface electron states that reside in the projected band gap around the (M) over bar point exhibit very different spin structures which are governed by the conventional and the cubic Rashba effect. The latter is reflected in a triple spin winding, i.e., the surface electron spin reveals three complete rotations upon moving once around the constant energy contours. Below the Ned temperature, our ARPES measurements show an intricate photoemission intensity picture characteristic of a complex magnetic domain structure. The orientation of the domains, however, can be clarified from a comparative analysis of the ARPES data and their DFT modeling. To characterize a single magnetic domain picture, we resort to the calculations and scrutinize the interplay of the Rashba spin-orbit coupling field with the in-plane exchange field, provided by the ferromagnetically ordered 4f moments of the near-surface Gd layer

Long-lived spin waves in a metallic antiferromagnet

Collective spin excitations in magnetically ordered crystals, called magnons or spin waves, can serve as carriers in novel spintronic devices with ultralow energy consumption. The generation of well-detectable spin flows requires long lifetimes of high-frequency magnons. In general, the lifetime of spin waves in a metal is substantially reduced due to a strong coupling of magnons to the Stoner continuum. This makes metals unattractive for use as components for magnonic devices. Here, we present the metallic antiferromagnet CeCo2P2, which exhibits long-living magnons even in the terahertz (THz) regime. For CeCo2P2, our first-principle calculations predict a suppression of low-energy spin-flip Stoner excitations, which is verified by resonant inelastic X-ray scattering measurements. By comparison to the isostructural compound LaCo2P2, we show how small structural changes can dramatically alter the electronic structure around the Fermi level leading to the classical picture of the strongly damped magnons intrinsic to metallic systems. Our results not only demonstrate that long-lived magnons in the THz regime can exist in bulk metallic systems, but they also open a path for an efficient search for metallic magnetic systems in which undamped THz magnons can be excited.This work was supported by the German Research Foundation (DFG) through Grants No. KR3831/5-1, No. LA655/20-1m, Fermi-NEst, GRK1621, TRR288 (No. 422213477) project A03, and SFB1143 (No. 247310070). D.V.V. acknowledges support from the Spanish Ministry of Science and Innovation, project PID2020-116093RB-C44, funded by MCIN/AEI/10.13039/ 501100011033. A.E. acknowledges funding by Fonds zur Förderung der wissenschaftlichen Forschung (FWF) grant I 5384. Part of the calculations were performed at Rechenzentrum Garching of the Max Planck Society (Germany). The authors acknowledge the ESRF for beamtime on beamline ID32.Peer reviewe

Insight into the electronic structure of the centrosymmetric skyrmion magnet GdRu2Si2

The discovery of a square magnetic-skyrmion lattice in GdRu2Si2, with the smallest so far found skyrmion size and without a geometrically frustrated lattice, has attracted significant attention. In this work, we present a comprehensive study of surface and bulk electronic structures of GdRu2Si2 by utilizing momentum-resolved photoemission (ARPES) measurements and first-principles calculations. We show how the electronic structure evolves during the antiferromagnetic transition when a peculiar helical order of 4f magnetic moments within the Gd layers sets in. A nice agreement of the ARPES-derived electronic structure with the calculated one has allowed us to characterize the features of the Fermi surface (FS), unveil the nested region along kz at the corner of the 3D FS, and reveal their orbital compositions. Our findings suggest that the Ruderman–Kittel–Kasuya–Yosida interaction plays a decisive role in stabilizing the spiral-like order of Gd 4f moments responsible for the skyrmion physics in GdRu2Si2. Our results provide a deeper understanding of electronic and magnetic properties of this material, which is crucial for predicting and developing novel skyrmion-based systems.We acknowledge the German Research Foundation (DFG) for the support through the grants no. KR3831/5-1, no. LA655/20-1, SFB1143 (project no. 247310070), and TRR288 (no. 422213477, project no. A03). The density functional theory calculations were supported by the Government research assignment for ISPMS SB RAS (project FWRW-2022-0001). E. V. C. acknowledges support from Saint Petersburg State University (project ID no. 94031444). V. S. S. and D. Y. U. work was partially supported by the Ministry of Science and Higher Education of the Russian Federation (no. FSMG-2023-0014) and RSF 23-72-30004. The calculations were partially performed using the equipment of the Shared Resource Center “Far Eastern Computing Resource” of IACP FEB RAS (https://cc.dvo.ru) and Joint Supercomputer Center of the Russian Academy of Sciences (https://rscgroup.ru/en/project/jscc). We also thank the Paul Scherrer Institut, Villigen, Switzerland, for the allocation of ARPES experiments at the ULTRA endstation of the SIS-X09LA beamline of the Swiss Light Source. We acknowledge MAX IV Laboratory for experimental time on beamline BLOCH under proposal 20211066. Research conducted at MAX IV, a Swedish national user facility, was supported by the Swedish Research Council under contract 2018-07152, the Swedish Governmental Agency for Innovation Systems under contract 2018-04969, and Formas under contract 2019-0249.Peer reviewe

Coulomb dissociation of N 20,21

Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N20,21 are reported. Relativistic N20,21 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the N19(n,γ)N20 and N20(n,γ)N21 excitation functions and thermonuclear reaction rates have been determined. The N19(n,γ)N20 rate is up to a factor of 5 higher at

Nuclear astrophysics with radioactive ions at FAIR

The nucleosynthesis of elements beyond iron is dominated by neutron captures in the s and r processes. However, 32 stable, proton-rich isotopes cannot be formed during those processes, because they are shielded from the s-process flow and r-process, β-decay chains. These nuclei are attributed to the p and rp process. For all those processes, current research in nuclear astrophysics addresses the need for more precise reaction data involving radioactive isotopes. Depending on the particular reaction, direct or inverse kinematics, forward or time-reversed direction are investigated to determine or at least to constrain the desired reaction cross sections. The Facility for Antiproton and Ion Research (FAIR) will offer unique, unprecedented opportunities to investigate many of the important reactions. The high yield of radioactive isotopes, even far away from the valley of stability, allows the investigation of isotopes involved in processes as exotic as the r or rp processes