Structural transition in epitaxial Co/Cr multilayers as studied by X-ray absorption spectroscopy

[[abstract]]We have performed Cr and Co K-edge x-ray-absorption measurements to investigate the dependence of local electronic and atomic structures on the Cr-layer thickness in epitaxial Co (40A)/Ct (t~) (t~ = 2, 3, 5, 7, and 9A) multilayers. The Cr K x-ray absorption near edge structure (XANES) spectra of Co/Cr multilayers indicate an abrupt transition of the Cr layer from a bcc structure to a hcp structure when the thickness of the Cr layer is decreased down to -5A or three atomic layers. The structural transition and bond-length distortion in Cr and Co layers observed in the extended x-ray absorption fine structure (EXAFS) measurements are consistent with the XANES results.[[notice]]補正完畢[[journaltype]]國外[[booktype]]紙本[[booktype]]電子版[[countrycodes]]US

Nonstoichiometric doping and Bi antisite defect in single crystal Bi2Se3

We studied the defects of Bi2Se3 generated from Bridgman growth of stoichiometric and nonstoichiometric self-fluxes. Growth habit, lattice size, and transport properties are strongly affected by the types of defect generated. Major defect types of Bi_Se antisite and partial Bi_2-layer intercalation are identified through combined studies of direct atomic-scale imaging with scanning transmission electron microscopy (STEM) in conjunction with energy-dispersive X-ray spectroscopy (STEM-EDX), X-ray diffraction, and Hall effect measurements. We propose a consistent explanation to the origin of defect type, growth morphology, and transport property.Comment: 5 pages, 5 figure

The Influence of Group Investigation Learning Model on College Students Learning Motivation Towards Environment Education

This study aims to analyze the influence of group investigation (GI) model on learning motivation of Student Environmental Education. This type of research is quasi experiment with non equivalent control group posttest only design. Research subjects consist of 2 semester students (2 classes) selected based on the value of Middle Semester Exam (UTS) odd semester of academic year 2017-2018 which has the average value is almost the same (homogeneous). The control class uses lecture and discussion models, while the experimental class uses the GI model. The instrument used to measure learning motivation is A Manual for the Use of the Motivated Strategies for Learning Questionnaire (MSLQ) developed by Pintrich et al. Further data obtained were analyzed by using Independent Sample T-Test Test with the help of SPSS 16.0 for Windows program. The results of this study indicate that there is a significant influence of GI model on the motivation to learn the environment of mahMahasiswa. It was based on the analysis results of the Independent Sample T-Test Test that showed the p-level 0.000. The p-level value is less than 0.05 (p <0.05). Key words: Group Investigation model, motivation to learn Environmental Education Studen

Virtual-pion and two-photon production in pp scattering

Two-photon production in pp scattering is proposed as a means of studying virtual-pion emission. Such a process is complementary to real-pion emission in pp scattering. The virtual-pion signal is embedded in a background of double-photon bremsstrahlung. We have developed a model to describe this background process and show that in certain parts of phase space the virtual-pion signal gives significant contribution. In addition, through interference with the two-photon bremsstrahlung background, one can determine the relative phase of the virtual-pion process

Strong correlations and orbital texture in single-layer 1T-TaSe2

Strong electron correlation can induce Mott insulating behaviour and produce intriguing states of matter such as unconventional superconductivity and quantum spin liquids. Recent advances in van der Waals material synthesis enable the exploration of Mott systems in the two-dimensional limit. Here we report characterization of the local electronic properties of single- and few-layer 1T-TaSe2 via spatial- and momentum-resolved spectroscopy involving scanning tunnelling microscopy and angle-resolved photoemission. Our results indicate that electron correlation induces a robust Mott insulator state in single-layer 1T-TaSe2 that is accompanied by unusual orbital texture. Interlayer coupling weakens the insulating phase, as shown by reduction of the energy gap and quenching of the correlation-driven orbital texture in bilayer and trilayer 1T-TaSe2. This establishes single-layer 1T-TaSe2 as a useful platform for investigating strong correlation physics in two dimensions

Dynamical model for Pion - Nucleon Bremsstrahlung

A dynamical model based on effective Lagrangians is proposed to describe the bremsstrahlung reaction $\pi N \to \pi N \gamma$ at low energies. The $\Delta(1232)$ degrees of freedom are incorporated in a way consistent with both, electromagnetic gauge invariance and invariance under contact transformations. The model also includes the initial and final state rescattering of hadrons via a T-matrix with off-shell effects. The $\pi N \gamma$ differential cross sections are calculated using three different T-matrix models and the results are compared with the soft photon approximation, and with experimental data. The aim of this analysis is to test the off-shell behavior of the different T-matrices under consideration.Comment: 16 pages, latex, 6 eps figures. Accepted for publication in Physical Review

Visualizing Exotic Orbital Texture in the Single-Layer Mott Insulator 1T-TaSe2

Mott insulating behavior is induced by strong electron correlation and can lead to exotic states of matter such as unconventional superconductivity and quantum spin liquids. Recent advances in van der Waals material synthesis enable the exploration of novel Mott systems in the two-dimensional limit. Here we report characterization of the local electronic properties of single- and few-layer 1T-TaSe2 via spatial- and momentum-resolved spectroscopy involving scanning tunneling microscopy and angle-resolved photoemission. Our combined experimental and theoretical study indicates that electron correlation induces a robust Mott insulator state in single-layer 1T-TaSe2 that is accompanied by novel orbital texture. Inclusion of interlayer coupling weakens the insulating phase in 1T-TaSe2, as seen by strong reduction of its energy gap and quenching of its correlation-driven orbital texture in bilayer and trilayer 1T-TaSe2. Our results establish single-layer 1T-TaSe2 as a useful new platform for investigating strong correlation physics in two dimensions