scholarly journals Dzyaloshinskii–Moriya Coupling in 3d Insulators

2019 ◽  
Vol 4 (4) ◽  
pp. 84 ◽  
Author(s):  
Alexander Moskvin
Keyword(s):  
Density Functional ◽  
Microscopic Theory ◽  
Strongly Correlated ◽  
Spin Orbital ◽  
Functional Theory ◽  
Different Types ◽  
Theoretical Results ◽  
Spin Orbital Coupling ◽  
Density Transfer ◽  
Super Exchange Interaction

We present an overview of the microscopic theory of the Dzyaloshinskii–Moriya (DM) coupling in strongly correlated 3d compounds. Most attention in the paper centers around the derivation of the Dzyaloshinskii vector, its value, orientation, and sense (sign) under different types of the (super)exchange interaction and crystal field. We consider both the Moriya mechanism of the antisymmetric interaction and novel contributions, in particular, that of spin–orbital coupling on the intermediate ligand ions. We have predicted a novel magnetic phenomenon, weak ferrimagnetism in mixed weak ferromagnets with competing signs of Dzyaloshinskii vectors. We revisit a problem of the DM coupling for a single bond in cuprates specifying the local spin–orbital contributions to the Dzyaloshinskii vector focusing on the oxygen term. We predict a novel puzzling effect of the on-site staggered spin polarization to be a result of the on-site spin–orbital coupling and the cation-ligand spin density transfer. The intermediate ligand nuclear magnetic resonance (NMR) measurements are shown to be an effective tool to inspect the effects of the DM coupling in an external magnetic field. We predict the effect of a strong oxygen-weak antiferromagnetism in edge-shared CuO 2 chains due to uncompensated oxygen Dzyaloshinskii vectors. We revisit the effects of symmetric spin anisotropy directly induced by the DM coupling. A critical analysis will be given of different approaches to exchange-relativistic coupling based on the cluster and the DFT (density functional theory) based calculations. Theoretical results are applied to different classes of 3d compounds from conventional weak ferromagnets ( α -Fe 2 O 3 , FeBO 3 , FeF 3 , RFeO 3 , RCrO 3 , ...) to unconventional systems such as weak ferrimagnets (e.g., RFe 1 - x Cr x O 3 ), helimagnets (e.g., CsCuCl 3 ), and parent cuprates (La 2 CuO 4 , ...).

scholarly journals Predicting the strain-mediated topological phase transition in 3D cubic ThTaN3

2018 ◽  
Vol 9 ◽  
pp. 1399-1404 ◽  
Author(s):  
Chunmei Zhang ◽  
Aijun Du
Keyword(s):  
Band Gap ◽  
Topological Insulator ◽  
Density Functional ◽  
Compressive Strain ◽  
Fermi Velocity ◽  
Spin Orbital ◽  
Functional Theory ◽  
Topological Phase Transition ◽  
Potential Applications ◽  
Spin Orbital Coupling

The cubic ThTaN3 compound has long been known as a semiconductor with a band gap of approximately 1 eV, but its electronic properties remain largely unexplored. By using density functional theory, we find that the band gap of ThTaN3 is very sensitive to the hydrostatic pressure/strain. A Dirac cone can emerge around the Γ point with an ultrahigh Fermi velocity at a compressive strain of 8%. Interestingly, the effect of spin–orbital coupling (SOC) is significant, leading to a band gap reduction of 0.26 eV in the ThTaN3 compound. Moreover, the strong SOC can turn ThTaN3 into a topological insulator with a large inverted gap up to 0.25 eV, which can be primarily attributed to the inversion between the d-orbital of the heavy element Ta and the p-orbital of N. Our results highlight a new 3D topological insulator with strain-mediated topological transition for potential applications in future spintronics.

First-Principles Study of Triangle Terarylene as a Possible Optical Molecular Switch

2011 ◽  
Vol 311-313 ◽  
pp. 526-529
Author(s):  
Cai Juan Xia ◽  
Han Chen Liu ◽  
Ji Xin Yin
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Molecular Switch ◽  
Optical Switches ◽  
Functional Theory ◽  
Closed Ring ◽  
Potential Applications ◽  
Homo Lumo ◽  
Non Equilibrium Green’S Function ◽  
Theoretical Results

Using non-equilibrium Green’s function formalism combined with first-principles density functional theory, we investigate the electronic transport properties of a triangle terarylene(open- and closed-ring forms) optical molecular switch. The influence of the HOMO-LUMO gaps and the spatial distributions of molecular orbitals on the quantum transport through the molecular device is discussed. Theoretical results show that the conductance of the closed-ring is 3-8 times larger than that of open-ring, which expect that this system can be one of good candidates for optical switches due to this unique advantage, and may have some potential applications in future molecular circuit.

scholarly journals CO2 activation through silylimido and silylamido zirconium hydrides supported on N-donor chelating SBA15 surface ligands

2016 ◽  
Vol 52 (12) ◽  
pp. 2577-2580 ◽  
Author(s):  
Farhan Ahmad Pasha ◽  
Anissa Bendjeriou-Sedjerari ◽  
Edy Abou-Hamad ◽  
Kuo-Wei Huang ◽  
Jean-Marie Basset
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Solid State Nmr ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Co2 Activation ◽  
Functional Theory ◽  
Surface Ligands ◽  
Different Types ◽  
Zirconium Hydrides

Density functional theory calculations and 2D 1H–13C HETCOR solid state NMR spectroscopy prove that CO2 can be used to probe, by its own reactivity, different types of N-donor surface ligands on SBA15-supported ZrIV hydrides: [(Si–O–)(Si–N)[Zr]H] and [(Si–NH–)(Si–X–)[Zr]H2] (XO or NH).

scholarly journals Predicting the conductance of strongly correlated molecules: the Kondo effect in perchlorotriphenylmethyl/Au junctions

Nanoscale ◽  
2018 ◽  
Vol 10 (37) ◽  
pp. 17738-17750 ◽  
Author(s):  
W. H. Appelt ◽  
A. Droghetti ◽  
L. Chioncel ◽  
M. M. Radonjić ◽  
E. Muñoz ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Perturbation Theory ◽  
First Principles ◽  
Density Functional ◽  
Kondo Effect ◽  
Strongly Correlated ◽  
Functional Theory ◽  
Molecular Conductance ◽  
Non Equilibrium

We predict the non-equilibrium molecular conductance in the Kondo regime from first principles by combining density functional theory with the renormalized super-perturbation theory.

XPS, AES AND UPS INVESTIGATION OF SnO2/Si AND DFT-BASED THEORETICAL STUDY WITHIN THE mBJ-GGA SCHEME

2020 ◽  
pp. 2050048
Author(s):  
A. MOKADEM ◽  
M. BOUSLAMA ◽  
B. KHAROUBI ◽  
A. OUERDANE ◽  
R. KHENATA ◽  
...  
Keyword(s):  
Valence Band ◽  
Density Of States ◽  
Photoelectron Spectroscopy ◽  
Density Functional ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Electronic Distribution ◽  
Complementary Techniques ◽  
Uv Photoelectron Spectroscopy ◽  
Theoretical Results

We investigate the growth performance of tin oxide on the Si substrate, achieved by spray pyrolysis using the sensitive analysis techniques X-Ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES). These complementary techniques confirm the growth of homogeneous SnO2 thin films. We also study the electronic distribution of the valence band of SnO2 theoretically using density functional theory (DFT). The chemical and physical properties of the material depend on the electron structure varying as a function of energy. The density of states (DOS) is calculated using the modified Becke–Johnson-Generalized Gradient Approximation (mBJ-GGA) in order to identify the electronic orbitals and the importance of their contribution to the electronic structure of the valence band. Furthermore, we use the experimental technique UV Photoelectron Spectroscopy (UPS) for studying the electronic distribution within the valence band and for validating the theoretical results of the density of states of SnO2/Si.

Spin density transfer from guest to host in endohedral heterofullerene dimers

2019 ◽  
Vol 21 (14) ◽  
pp. 7605-7612
Author(s):  
Vinit Vinit ◽  
C. N. Ramachandran
Keyword(s):  
Density Functional Theory ◽  
Spin Density ◽  
Density Functional ◽  
Functional Theory ◽  
Density Transfer

The endohedral heterofullerenes (B@C59B)2, (B@C59N)2, (N@C59B)2 and (B@C59N–N@C59B) are investigated using dispersion corrected density functional theory.

scholarly journals Symmetry/Asymmetry of the NHN Hydrogen Bond in Protonated 1,8-Bis(dimethylamino)naphthalene

Symmetry ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1924
Author(s):  
Patrycja Piękoś ◽  
Aneta Jezierska ◽  
Jarosław J. Panek ◽  
Eugene A. Goremychkin ◽  
Alexander F. Pozharskii ◽  
...  
Keyword(s):  
Density Functional ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Functional Theory ◽  
Protonated Forms ◽  
Motional Dynamics ◽  
Proton Dynamics ◽  
Experimental Findings ◽  
Bridge Vibrations ◽  
Theoretical Results

Experimental and theoretical results are presented based on vibrational spectra and motional dynamics of 1,8-bis(dimethylamino)naphthalene (DMAN) and its protonated forms (DMANH+ and the DMANH+ HSO4− complex). The studies of these compounds have been performed in the gas phase and solid-state. Spectroscopic investigations were carried out by infrared spectroscopy (IR), Raman, and incoherent inelastic neutron scattering (IINS) experimental methods. Density functional theory (DFT) and Car–Parrinello molecular dynamics (CPMD) methods were applied to support our experimental findings. The fundamental investigations of hydrogen bridge vibrations were accomplished on the basis of isotopic substitutions (NH → ND). Special attention was paid to the bridged proton dynamics in the DMANH+ complex, which was found to be affected by interactions with the HSO4− anion.

Scaled quantum mechanical force fields for trifluoromethyl selenium derivatives. I. The CF3SeCN and CF3SeCH3 molecules

2006 ◽  
Vol 84 (12) ◽  
pp. 1626-1631 ◽  
Author(s):  
L E Fernández ◽  
E L Varetti
Keyword(s):  
Density Functional ◽  
Force Fields ◽  
Chemical Species ◽  
Mechanical Force ◽  
Force Constants ◽  
Quantum Mechanical ◽  
Functional Theory ◽  
Definition Of ◽  
Theoretical Results ◽  
Mechanical Force Fields

Force fields and vibrational properties were calculated for the trifluoromethyl selenium derivatives, CF3SeCN and CF3SeCH3, by means of density functional theory (DFT) techniques. The existing experimental data and assignments for these molecules were confirmed by the theoretical results. These data were subsequently used in the definition of scaled quantum mechanical force fields for such chemical species. The obtained force constants are compared with results previously published for similar compounds.Key words: trifluoromethyl selenium, force constants, structure, DFT calculation.

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