scholarly journals Measuring the sense of the Dzyaloshinskii–Moriya interaction

2014 ◽  
Vol 70 (a1) ◽  
pp. C1350-C1350
Author(s):  
Vladimir Dmitrienko ◽  
Elena Ovchinnikova ◽  
Steve Collins ◽  
Gareth Nisbet ◽  
Guillaume Beutier ◽  
...  
Keyword(s):  
Local Density ◽  
Magnetic Moments ◽  
Resonant Scattering ◽  
Spin Orbit ◽  
Ministry Of Education ◽  
Multiple Diffraction ◽  
Dm Interaction ◽  
Antiferromagnetic Ordering ◽  
Theoretical Approaches ◽  
Grant Program

The spin-orbit Dzyaloshinskii–Moriya (DM) interaction EDM=D·[s1×s2] can induce small canting of neighboring magnetic moments s1 and s2. It is also very important for multiferroics and helimagnetic MnSi-type crystals with the spiral or Skyrmionic structures. The sense of the DM vector D has been experimentally determined for the first time in canted antiferromagnetic FeBO3 crystal [1]. The technique of interference between magnetic and resonant channels in synchrotron x-ray scattering was exploited. The phase of antiferromagnetic ordering (and scattering) was fixed by external magnetic field and the phase of resonant scattering was calculated with FDMNES program. Similar experiments have been also performed for MnCO3 and CoCO3 crystals. For Fe2O3 hematite crystal, the technique of interference between magnetic and multiple diffraction channels has been used. The experimental measurements are supported by ab initio calculations of the DM interaction. The first-principles calculations have been performed with Local Density Approximation incorporating the on-site Coulomb interaction U and the Spin-Orbit coupling (LDA+U+SO) [2,3]. It was found how DM interaction depends on displacements of oxygen atoms. These experimental and theoretical approaches open up new possibilities for exploring, modeling and exploiting novel magnetic and multiferroic materials. VED and ENO are grateful to the RFBR research project No. 13-02-00760 and to the project of Presidium of Russian Academy of Sciences No. 24. The work of VVM is supported by the grant program of President of Russian Federation MK-5565.2013.2, the contracts of the Ministry of education and science of Russia N 14.A18.21.0076 and 14.A18.21.0889. MIK acknowledges a financial support by FOM (The Netherlands).

Magnetic Properties of Embedded Rh Clusters in Ni Matrix

1995 ◽  
Vol 384 ◽  
Author(s):  
Zhi-Qiang Li ◽  
Yuichi Hashi ◽  
Jing-Zhi Yu ◽  
Kaoru Ohno ◽  
Yoshiyuki Kawazoe
Keyword(s):  
Magnetic Properties ◽  
Electronic Structure ◽  
First Principles ◽  
Density Functional ◽  
Local Density ◽  
Magnetic Moments ◽  
Functional Formalism ◽  
Rhodium Clusters ◽  
Spin Polarized ◽  
Local Density Functional

ABSTRACTThe electronic structure and magnetic properties of rhodium clusters with sizes of 1 - 43 atoms embedded in the nickel host are studied by the first-principles spin-polarized calculations within the local density functional formalism. Single Rh atom in Ni matrix is found to have magnetic moment of 0.45μB. Rh13 and Rhl 9 clusters in Ni matrix have lower magnetic moments compared with the free ones. The most interesting finding is tha.t Rh43 cluster, which is bulk-like nonmagnetic in vacuum, becomes ferromagnetic when embedded in the nickel host.

III. Energy Bands, Fermi Surfaces and Density of States of the Hole Carriers in the Presence of the Local Antiferromagnetic Ordering

1997 ◽  
Vol 11 (32) ◽  
pp. 3759-3796 ◽  
Author(s):  
Hideki Ushio ◽  
Hiroshi Kamimura
Keyword(s):  
Energy Band ◽  
Density Functional ◽  
Local Density ◽  
Density Functional Method ◽  
Mean Free Path ◽  
Linear Temperature Dependence ◽  
Energy Bands ◽  
Fermi Surfaces ◽  
Linear Temperature ◽  
Antiferromagnetic Ordering

We have separated a hole carrier and a localized spin, by treating the exchange interaction between the spins of a carrier hole and a localized spin in a mean field sense. Then we have constructed the effective one-electron-type band structure for the hole carriers in the presence of the antiferromagnetic (AF) ordering of the localized spins. In the case of the undoped La2CuO4 all the energy bands are fully occupied by electrons so that La2CuO4 is an insulator. In this sense the present energy bands which include the many body effect fully is completely different from the ordinary energy band in the local density functional method. The top of the highest valence band is at (π/a, π/a, 0)-point, and the calculated Fermi surface is small as far as the spin correlation length of the AF order is larger than the mean free path. Based on this energy band and Fermi surfaces we have calculated various normal state properties and explained their anomalous features, such as the x-dependence of the electronic specific heat, the linear temperature dependence of the resistivity down to T c , the x-dependence of the Hall coefficient with the sign change, the large T dependence of R H , the incommensurate peak of the neutron scattering and the instability at x=0.125.

ENHANCEMENT OF Fe MAGNETIC MOMENTS IN FERROMAGNETIC Fe16B2, Fe16C2, AND Fe16N2

1993 ◽  
Vol 07 (01n03) ◽  
pp. 729-732 ◽  
Author(s):  
B.I. MIN
Keyword(s):  
Magnetic Moment ◽  
Density Functional ◽  
Local Density ◽  
Magnetic Moments ◽  
Local Environment ◽  
Electronic Structure Calculations ◽  
Orbital Contribution ◽  
Large Enhancement ◽  
Band Method ◽  
Structure Calculations

In order to investigate electronic and magnetic properties of Fe16X2 (X=B, C, N) ferromagnet, we have performed electronic structure calculations employing the total energy self-consistent local density functional linearized muffin tin orbital (LMTO) band method. Large enhancement of the magnetic moment is observed in FeII and FeIII, which are located farther from X than FeI. This suggests that the local environment plays a very important role in determining Fe magnetic moments in these compounds. Orbital contribution to the magnetic moment in Fe atoms of Fe16N2 is minor, totalof ~0.6 μB in the unit cell. We have obtained the average magnetic moments per Fe atom, 2.30, 2.40, and 2.50 μB, in Fe16B2, Fe16C2, and Fe16N2, respectively.

scholarly journals Magnetic Properties of the Bismuth Oxide α — Bi2O3

1996 ◽  
Vol 51 (5-6) ◽  
pp. 665-666 ◽  
Author(s):  
A.I. Kharkovskii ◽  
V.l. Nizhankovskii ◽  
E. A. Kravchenko ◽  
V. G. Orlov
Keyword(s):  
Magnetic Properties ◽  
Bismuth Oxide ◽  
Magnetoelectric Effect ◽  
Magnetic Moments ◽  
Magnetic Behaviour ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Physical Origin ◽  
Wide Range ◽  
Electric Dipoles

Abstract A very unusual magnetic behaviour of α - Bi2O3 was observed in a wide range of temperatures and magnetic fields. A longitudinal magnetoelectric effect was found at 4.2 K. The existence of an antiferroelectrically ordered subsystem of electric dipoles in α - Bi2O3is proposed. The mechanism of spin-orbit coupling is regarded as the physical origin for the occurrence of the ordered magnetic moments in α - Bi2O3.

Structural and Electronic Properties of Hydrogen-Passivated Silicon Quantum Dots: Density Functional Calculations

2015 ◽  
Vol 1107 ◽  
pp. 571-576 ◽  
Author(s):  
Muhammad Mus-'ab Anas ◽  
Ahmad Puaad Othman ◽  
Geri Gopir
Keyword(s):  
Quantum Dots ◽  
Density Functional ◽  
Energy Gap ◽  
Local Density ◽  
Basis Set ◽  
Face Centered Cubic ◽  
Hydrogen Atoms ◽  
Silicon Quantum Dots ◽  
Theoretical Approaches ◽  
Passivated Silicon

Density functional theory (DFT) by numerical basis-set calculations of silicon quantum dots (Si-QDs) passivated by hydrogen, ranging in size up to 1.9 nm are presented. These DFT computation results are used to examine and deduce the properties of 14 spherical Si-QDs including its density of state (DOS), and energy gap from the HOMO-LUMO results. The atomistic model of each silicon QDs was constructed by repeating crystal unit cell of face-centered cubic (FCC) structure, then the QDs surface was passivated by hydrogen atoms. The model was relaxed and optimized using Quasi-Newton method for each size of Si-QDs to get an ideal structure. Exchange-correlation potential (Vxc) of electrons were approximated in this system using the Local Density Approximation (LDA) functional and Perdew-Zunger (PZ) functional. Finally, all results were compared with previous experimental data and other similar theoretical approaches, and these results augured well

scholarly journals 5f Delocalization of Bulk FCC Americium and the (111) Surface: A FP-LAPW Electronic Structure Study

2005 ◽  
Vol 893 ◽  
Author(s):  
Da Gao ◽  
Asok K Ray
Keyword(s):  
Electronic Properties ◽  
Local Density ◽  
Structure Study ◽  
Orbit Coupling ◽  
Full Potential ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Generalized Gradient ◽  
Quantum Size ◽  
Ferromagnetic Ground State

AbstractThe electronic properties of bulk fcc americium and the (111) surface have been investigated with the full-potential linearized augmented plane wave (FP-LAPW) method as implemented in the WIEN2K suite of programs The study is carried out for the anti-ferromagnetic ground state of Am at different levels of theory: (1) scalar-relativity vs. full-relativity; (2) local-density approximation (LDA) vs. generalized-gradient approximation (GGA). Our results indicate that spin orbit coupling plays an important role in determining the electronic properties of both bulk fcc americium and the (111) surface. In general, LDA is found to give a higher total energy compared to GGA results. The spin orbit coupling shows a similar effect on the surface calculations regardless of the model, GGA versus LDA. The 5f localized-delocalized transition of americium is employed to explain our results. In addition, the quantum size effects in the surface energies and the work functions of fcc (111) americium ultra thin films (UTF) are also examined.

Intermetallic Cadmium Compounds M5T2Cd (M = Ca, Yb, Eu; T = Cu, Ag, Au) with Mo5B2Si-type Structure

2011 ◽  
Vol 66 (12) ◽  
pp. 1219-1224
Author(s):  
Frank Tappe ◽  
Christian Schwickert ◽  
Matthias Eul ◽  
Rainer Pöttgen
Keyword(s):  
Magnetic Moments ◽  
Small Degree ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Pauli Paramagnetism ◽  
Slab Temperature ◽  
Experimental Magnetic Moment ◽  
The Eu

The intermetallic compounds M5T2Cd (M = Ca, Yb, Eu; T = Cu, Ag, Au) and Yb5Cu2Zn were synthesized by melting the elements in sealed tantalum tubes followed by annealing at 923 K. All phases were characterized on the basis of powder and single-crystal X-ray diffraction data: Mo5B2Si type, I4/mcm, Z = 4, a = 828.7(1), c = 1528.1(3) pm, wR2 = 0.030, 440 F2 values, 16 variables for Eu5Cu2Cd, a = 788.2(1), c = 1459.3(5) pm, wR2 = 0.053, 378 F2 values, 16 variables for Yb5Cu2Cd, and a = 797.2(1), c = 1438.8(3) pm, wR2 = 0.036, 386 F2 values, 17 variables for Yb5Au2.19Cd0.81, which shows a small degree of Au / Cd mixing. The M5T2Cd structures are intergrowth variants of slightly distorted CuAl2- and U3Si2-related slabs. Striking coordination motifs (exemplary for Eu5Cu2Cd) are square antiprisms of the Eu atoms around Cd, Eu8 square prisms around Eu, and trigonal Eu6 prisms around Cu within the AlB2-related slab. Temperature-dependent magnetic susceptibility measurements showed Pauli paramagnetism for Yb5Cu2Zn, indicating purely divalent ytterbium. Eu5Au2Cd exhibits Curie-Weiss behavior above 100 K with an experimental magnetic moment of 8.14 μB per Eu atom and a Weiss constant of 56 K. Antiferromagnetic ordering of the EuII magnetic moments is evident at 36 K, and a metamagnetic transition is observed at 25 K and 13 kOe.

The restoration of Wigner’s SU(4)-symmetry in the superheavy nucleus and its correlation with the problem “island of stability”, or does the “island of stability” exist?

2016 ◽  
Vol 31 (27) ◽  
pp. 1650145 ◽  
Author(s):  
A. M. Nurmukhamedov
Keyword(s):  
Mass Formula ◽  
Superheavy Nucleus ◽  
Orbit Interaction ◽  
Theoretical Research ◽  
Superheavy Nuclei ◽  
Isospin Symmetry ◽  
Spin Orbit ◽  
Atomic Nuclei ◽  
Theoretical Approaches ◽  
Better Than

This paper reviews the history and stages of experimental verification of the hypothesis of Wigner’s spin–isospin SU(4)-symmetry restoration in the field of heavy atomic nuclei and its implications on hypothesis of the “island of stability”. Energies of [Formula: see text]-decay of a number of [Formula: see text]-chains of new superheavy nuclei were calculated based on Wigner’s mass formula without contribution of spin–orbit interaction that correspond to the restoration of Wigner’s spin–isospin symmetry. Calculated energies of the [Formula: see text]-decay fit the experimental data better than other theoretical approaches. It is concluded that there is a need to continue theoretical research of the “island of stability” taking into account mechanisms of restoration of Wigner’s spin–isospin SU(4)-symmetry.

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