Theoretical Studies on the Magnetic Moments of Iron Nitrides Including Fe16N2

1993 ◽  
Vol 313 ◽  
Author(s):  
Akimasa Sakuma ◽  
Yutaka Sugita
Keyword(s):  
Magnetic Moment ◽  
Density Functional ◽  
Magnetic Moments ◽  
Iron Nitrides ◽  
Functional Formalism ◽  
Orbital Magnetic Moment ◽  
Spin Polarized ◽  
Calculated Magnetic Moment ◽  
The Difference

ABSTRACTThe spin-polarized band calculations for the iron nitrides, Fe3N, Fe4N and Fe16N2, have been performed with use of LMTO-ASA Method in the frame of local spin density functional formalism. The results show that the most distant Fe atoms from N have the largest magnetic moment. The central role of the N atom is to bring about the large magnetic moments through the lattice expansion. Concurrently, the N atoms promote an itinerancy of electrons and then in turn prevent the exchange-splitting. This results in an Fe16N2 with the lowest N concentration having the largest magnetic moments. Quantitatively, the obtained magnetic moments are in fair agreements with the experimental results except for Fe16Nr The calculated magnetic moment of Fe6N2 is about 2.4 ΜB/Pε, while the measured value is reported as 3.5 ΜB/FB. The orbital magnetic moment of Fe16N2 is about 0.07 ΜB, which is too small to make up for the difference from the experimental value.

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.

Stable ferromagnetic state in Si-doped AlN with cation vacancies: Ab-initio study

2016 ◽  
Vol 05 (03) ◽  
pp. 1650017
Author(s):  
Sandhya Chintalapati ◽  
Yuan Ping Feng
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Magnetic Moments ◽  
Ferromagnetic State ◽  
First Principles Calculations ◽  
Ab Initio Study ◽  
Functional Theory ◽  
Spin Polarized ◽  
Si Doped

The magnetic property of Si-doped AlN with Al-vacancy is studied using first principles calculations based on spin polarized density functional theory. The Si dopant alone does not introduce the magnetic moment in AlN. However, the doping of Si in AlN reduces the formation energy caused by Al-vacancy, and stabilizes the spin polarized state. The magnetic moments are mainly localized on N atoms surrounding the defect. The strong ferromagnetic state is obtained in AlN due to the combined role of Al-vacancy and Si-dopant.

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.

Electronic and Magnetic Properties of Ternary Stannides RERhSn (RE = Tb, Dy and Ho)

2011 ◽  
Vol 170 ◽  
pp. 74-77 ◽  
Author(s):  
Kazimierz Łątka ◽  
Jacek Gurgul ◽  
Andrzej W. Pacyna ◽  
Rainer Pöttgen
Keyword(s):  
Magnetic Properties ◽  
Electric Field ◽  
Magnetic Moment ◽  
Magnetic Moments ◽  
Magnetic Studies ◽  
Crystalline Electric Field ◽  
Electric Field Effects ◽  
Electronic And Magnetic Properties ◽  
Field Effects

The results of magnetic studies and Mössbauer investigations made with 119Sn source are reviewed for the series of RERhSn (RE = Tb, Dy and Ho) compounds crystallizing in the same hexagonal ZrNiAl-type of structure. The role of crystalline electric field effects in the establishing of magnetic moment orientations observed in these compounds and their influence on the observed magnitudes of magnetic moments are discussed.

scholarly journals Tuning the Magnetic Moment of Small Late 3d-Transition-Metal Oxide Clusters by Selectively Mixing the Transition-Metal Constituents

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1814
Author(s):  
Rodrigo H. Aguilera-del-Toro ◽  
María B. Torres ◽  
Faustino Aguilera-Granja ◽  
Andrés Vega
Keyword(s):  
Transition Metal ◽  
Metal Oxide ◽  
Magnetic Moment ◽  
Density Functional ◽  
Magnetic Moments ◽  
Metal Oxide Nanoparticles ◽  
Transition Metal Oxide ◽  
Blocking Temperature ◽  
Oxide Nanoparticles ◽  
Oxidation Rates

Transition-metal oxide nanoparticles are relevant for many applications in different areas where their superparamagnetic behavior and low blocking temperature are required. However, they have low magnetic moments, which does not favor their being turned into active actuators. Here, we report a systematical study, within the framework of the density functional theory, of the possibility of promoting a high-spin state in small late-transition-metal oxide nanoparticles through alloying. We investigated all possible nanoalloys An−xBxOm (A, B = Fe, Co, Ni; n = 2, 3, 4; 0≤x≤n) with different oxidation rates, m, up to saturation. We found that the higher the concentration of Fe, the higher the absolute stability of the oxidized nanoalloy, while the higher the Ni content, the less prone to oxidation. We demonstrate that combining the stronger tendency of Co and Ni toward parallel couplings with the larger spin polarization of Fe is particularly beneficial for certain nanoalloys in order to achieve a high total magnetic moment, and its robustness against oxidation. In particular, at high oxidation rates we found that certain FeCo oxidized nanoalloys outperform both their pure counterparts, and that alloying even promotes the reentrance of magnetism in certain cases at a critical oxygen rate, close to saturation, at which the pure oxidized counterparts exhibit quenched magnetic moments.

scholarly journals The Role of the Active Site Tyrosine in the Mechanism of Lytic Polysaccharide Monooxygenase

2020 ◽  
Author(s):  
Aina McEvoy ◽  
Joel Creutzberg ◽  
Raushan Kumar Singh ◽  
Morten J. Bjerrum ◽  
Erik Hedegård
Keyword(s):  
Active Site ◽  
Density Functional ◽  
Renewable Resource ◽  
Lytic Polysaccharide Monooxygenase ◽  
Functional Theory ◽  
Polysaccharide Monooxygenases ◽  
Active Site Tyrosine ◽  
The Difference ◽  
First Time

Natural polysaccharides (such as cellulose) comprise a large bio-renewable resource. However, exploitation of this resource requires energy-efficient polysaccharide degradation, which is currently limited by the inherent recalcitrance of many naturally occurring polysaccharides. Catalytic breakdown of polysaccharides can be achieved more efficiently by means of the enzymes lytic polysaccharide monooxygenases (LPMOs). However, the LPMO mechanism has remained controversial, preventing full exploitation of their potential. One of the controversies has centered around an active site tyrosine, present in most LPMOs. Different roles for this tyrosine have been proposed without direct evidence, but two recent investigations have for the first time obtained direct (spectroscopic) evidence for that chemical modification of this tyrosine is possible. Surprisingly, the spectroscopic features obtained in the two investigations are remarkably different. In this paper we use density functional theory (DFT) in a QM/MM formulation to reconcile these (apparently) conflicting results. By modeling the spectroscopy as well as the underlying reaction mechanism we can show how formation of two isomers (both involving deprotonation of tyrosine) explain the difference in the experimental observed spectroscopic features. The link between our structures and the observed spectroscopy provides a firm ground to investigate the role of tyrosine.

scholarly journals Magnetic moment quenching in small Pd clusters in solution

2021 ◽  
Vol 75 (12) ◽  
Author(s):  
Sebastian Hammon ◽  
Linn Leppert ◽  
Stephan Kümmel
Keyword(s):  
Magnetic Moment ◽  
Density Functional ◽  
Magnetic Moments ◽  
Direct Consequence ◽  
Solvation Shell ◽  
Electronic Interaction ◽  
Cluster Geometry ◽  
Pd Clusters ◽  
Solvent Molecules ◽  
Dynamics Simulations

Abstract Small palladium clusters in vacuum show pronounced magnetic moments. With the help of Born–Oppenheimer molecular dynamics simulations based on density functional theory, we investigate for the paradigmatic examples of the Pd$$_{13}$$ 13 and the Pd$$_8$$ 8 cluster whether these magnetic moments prevail when the clusters are solvated. Our results show that the interaction with acetophenone quenches the magnetic moment. The reduction of the magnetic moment is a direct consequence of the electronic interaction between the Pd clusters and the solvent molecules, and not an indirect effect due to a different cluster geometry being stabilized by the solvation shell. Graphical Abstract

scholarly journals Density-Functional Tight-Binding for Platinum Clusters and Bulk: Electronic vs Repulsive Parameters

MRS Advances ◽  
2019 ◽  
Vol 4 (33-34) ◽  
pp. 1821-1832
Author(s):  
Ka Hung Lee ◽  
Van Quan Vuong ◽  
Victor Fung ◽  
De-en Jiang ◽  
Stephan Irle
Keyword(s):  
Density Functional ◽  
Tight Binding ◽  
General Purpose ◽  
Training Set ◽  
Functional Theory ◽  
Spin Polarized ◽  
Platinum Clusters ◽  
Electronic Parameters ◽  
Test Sets

ABSTRACTWe present a general purpose Pt-Pt density-functional tight-binding (DFTB) parameter for Pt clusters as well as bulk, using a genetic algorithm (GA) to automatize the parameterization effort. First we quantify the improvement possible by only optimizing the repulsive potential alone, and second we investigate the effect of improving the electronic parameter as well. During both parameterization efforts we employed our own training set and test sets, with one set containing ∼20,000 spin-polarized DFT structures. We analyze the performance of our two DFTB Pt-Pt parameter sets against density functional theory (DFT) as well as an earlier DFTB Pt-Pt parameters. Our study sheds light on the role of both repulsive and electronic parameters with regards to DFTB performance.

Influence of Co and Mn substitution on magnetic properties of novel Y2FeSi Heusler alloy

2021 ◽  
Vol 35 (05) ◽  
pp. 2150088
Author(s):  
G. Kasprzak ◽  
J. Rzacki
Keyword(s):  
Magnetic Properties ◽  
Spin Polarization ◽  
Magnetic Moment ◽  
Density Functional ◽  
Magnetic Moments ◽  
Heusler Alloys ◽  
Total Magnetic Moment ◽  
Functional Theory ◽  
Structure Changes ◽  
Mn Substitution

This paper presents results of density functional theory (DFT) studies on structural, electronic, and magnetic properties of novel Y2FeSi Heusler material characterized by spin polarization at Fermi level of [Formula: see text] and magnetic moment of 1.56 [Formula: see text]. The total magnetic moment of investigated material is dominated by Iron sites, while magnetic moments coming from Yttrium sites are aligned antiparallel to the Iron. Here, we introduced Co and Mn substitutions to alter the magnetic and electronic properties of the studied material. The Heusler alloys are very sensitive to electronic structure changes induced by ionic substitutions, which allowing to specifically modulate their properties. The Co-substitution lowered the total magnetic moment to [Formula: see text][Formula: see text]1.20 [Formula: see text] and Mn caused a rise to [Formula: see text][Formula: see text]1.93 [Formula: see text]. Introduction of Mn resulted in [Formula: see text] spin polarization. We hope that this study will promote further theoretical as well as experimental interest in these types of compounds.

A Density Functional Theory Study of Gd8O12 Cluster

2012 ◽  
Vol 542-543 ◽  
pp. 1418-1421
Author(s):  
Qing Xiang Gao ◽  
Lin Xu ◽  
Bo Wu
Keyword(s):  
Density Functional Theory ◽  
Magnetic Properties ◽  
Density Functional ◽  
Magnetic Moments ◽  
Generalized Gradient ◽  
Cage Structure ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Spin Polarized ◽  
Ionic Bonds

The spin-polarized generalized gradient approximation to the density functional theory is used to determine the geometries, stability, electronic structures, and magnetic properties of the Gd8O12cluster. Our work reveals that the ground state configuration of the Gd8O12cluster is a hexahedral cage structure with Cisymmetry. The electronic and magnetic properties imply that the formations of the ionic bonds between the adjacent Gd and O atoms result in the high stability of the Gd8O12cluster, which is due to the charge transfers between the Gd 5d, 6s electrons to O 2p orbital. It is also confirmed by the electron densities of HOMO-LUMO states. In addition, the analysis of the magnetic properties implies the total magnetic moments are mostly dominated by the Gd 4f orbital.

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