scholarly journals Understanding complex multiple sublattice magnetism in double double perovskites

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anita Halder ◽  
Shreya Das ◽  
Prabuddha Sanyal ◽  
Tanusri Saha-Dasgupta
Keyword(s):  
Magnetic Moment ◽  
Double Exchange ◽  
Magnetic Behavior ◽  
Double Perovskite ◽  
Exchange Mechanism ◽  
Double Perovskites ◽  
Half Metallic ◽  
Magnetic Sublattice ◽  
High Transition ◽  
Interesting Class

AbstractUnderstanding magnetism in multiple magnetic sublattice system, driven by the interplay of varied nature of magnetic exchanges, is on one hand challenging and on other hand intriguing. Motivated by the recent synthesis of AA$$^{\prime }$$ ′ BB$$^{\prime }$$ ′ O$$_6$$ 6 double double perovskites with multiple magnetic ions both at A- and B-sites, we investigate the mechanism of magnetic behavior in these interesting class of compounds. We find that the magnetism in such multiple sublattice compounds is governed by the interplay and delicate balance between two distinct mechanisms, (a) kinetic energy-driven multiple sublattice double exchange mechanism and (b) the conventional super-exchange mechanism. The derived spin Hamiltonian based on first-principles calculations is solved by classical Monte Carlo technique which reproduces the observed magnetic properties. Finally, the influence of off-stoichiometry, as in experimental samples, is discussed. Some of these double double perovskite compounds are found to possess large total magnetic moment and also are found to be half-metallic with reasonably high transition temperature, which raises the hope of future applications of these large magnetic moment half-metallic oxides in spintronics and memory devices.

scholarly journals Theory of half-metallic double perovskites. I. Double exchange mechanism

2013 ◽  
Vol 87 (16) ◽  
Author(s):  
O. Nganba Meetei ◽  
Onur Erten ◽  
Anamitra Mukherjee ◽  
Mohit Randeria ◽  
Nandini Trivedi ◽  
...  
Keyword(s):  
Double Exchange ◽  
Exchange Mechanism ◽  
Double Perovskites ◽  
Half Metallic

scholarly journals Half-Metallic Property Induced by Double Exchange Interaction in the Double Perovskite Bi2BB′O6 (B, B′ = 3d Transitional Metal) via First-Principles Calculations

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1844 ◽  
Author(s):  
Hong-Zong Lin ◽  
Chia-Yang Hu ◽  
Po-Han Lee ◽  
Albert Zhong-Ze Yan ◽  
Wen-Fang Wu ◽  
...  
Keyword(s):  
Exchange Interaction ◽  
Density Functional ◽  
Double Exchange ◽  
Double Perovskite ◽  
Transition Metal Ions ◽  
Spin Interaction ◽  
Metallic Materials ◽  
Generalized Gradient ◽  
Double Exchange Interaction ◽  
Half Metallic

In this paper, we identify three possible candidate series of half-metals (HM) from Bi-based double perovskites Bi2BB′O6 (BB′ = transition metal ions) through calculations utilizing the density functional theory (DFT) and full-structural optimization, in which the generalized gradient approximation (GGA) and the strong correlation effect (GGA + U) are considered. After observing the candidate materials under four types of magnetic states, i.e., ferromagnetic (FM), ferrimagnetic (FiM), antiferromagnetic (AF), and nonmagnetic (NM), we found eight promising candidates for half-metallic materials. Under the GGA scheme, there are three ferromagnetic-half-metal (FM-HM) materials, Bi2CrCoO6, Bi2CrNiO6 and Bi2FeNiO6, and three FiM-HM materials, Bi2FeZnO6, Bi2CrZnO6 and Bi2CoZnO6. With implementation of the Coulomb interaction correction (GGA + U), we find two stable half-metallic materials: Bi2CrNiO6 and Bi2CrZnO6. We determine that the stability of some of these materials are tied to the double exchange interaction, an indirect interaction within the higher powers of localized spin interaction among transition metals via oxygen ions. Found in half-metallic materials, and especially those in the ferromagnetic (FM) state, the double exchange interaction is recognized in the FM-HM materials Bi2CrCoO6 and Bi2FeNiO6.

THEORETICAL PREDICTION OF A NEW TYPE OF HALF-METALLIC MATERIALS IN DOUBLE DEROVSKITE Pb2BB′O6 (B, B′ = 3d TRANSITION METAL) VIA FIRST-PRINCIPLE CALCULATIONS

SPIN ◽  
2014 ◽  
Vol 04 (01) ◽  
pp. 1450001
Author(s):  
HUEI-RU FUH ◽  
KE-CHUAN WENG ◽  
YUN-PING LIU ◽  
YIN-KUO WANG
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Interaction Mechanism ◽  
Double Exchange ◽  
Double Perovskite ◽  
Generalized Gradient ◽  
Double Exchange Interaction ◽  
Half Metallic ◽  
Metal Atoms ◽  
Transition Metal Atoms

This study investigate the electronic structure of double perovskite Pb 2BB′ O 6 (B, B′ = 3d transition metal atoms) with ab initio calculation. Density functional theory with generalized gradient approximation (GGA) is used to determine the physical proprieties of the materials. Six new half-metallic (HM) materials are found from 45 [Formula: see text] combinations in double perovskite Pb 2BB′ O 6 (of 3d transition metal atoms). There are five ferromagnetic (FM)-HM materials ( Pb 2 ScCrO 6, Pb 2 ScMnO 6, Pb 2 TiVO 6, Pb 2 TiCrO 6 and Pb 2 CrMnO 6) and one ferrimagnetic (FiM)-HM material ( Pb 2 TiFeO 6). The HM property of the materials are attributed to the double-exchange interaction mechanism through the B(t2g)- O (2p)-B′(t2g) π-binding. Besides including the on site Coulomb interaction, GGA+U calculation is also carried out and the HM property is ensured.

Bulrush-Like Double Perovskite: Synthesis, Tunneling Magnetoresistance, and Magnetocaloric Effects

2008 ◽  
Vol 8 (6) ◽  
pp. 2793-2810 ◽  
Author(s):  
W. Zhong ◽  
N. J. Tang ◽  
C. T. Au ◽  
Y. W. Du
Keyword(s):  
Room Temperature ◽  
Recent Observation ◽  
Chemical Properties ◽  
Double Perovskite ◽  
Tunneling Magnetoresistance ◽  
Double Perovskites ◽  
New Approach ◽  
Half Metallic ◽  
Physical And Chemical ◽  
And Chemical Properties

The recent observation of room temperature tunneling magnetoresistance (TMR) in half-metallic A2FeMoO6 (A = Ca, Sr, Ba) double perovskites, and their importance to the emerging field of spintronics has led to considerable effort being dedicated to detailed investigations of the physical and chemical properties of these materials. This article will present an review of our recent investigations covering the synthesis, structures, magnetic and transport properties of "bulrush-like" A2FeMoO6 (A = Sr, Ba). Utilizing the high shape anisotropy as well as the reactivity of A2FeMoO6 to water and a sonochemical technique, we managed to manipulate the properties of grain boundary barriers, and thus put forward a new approach for the enhancement of room temperature TMR. The magnetocaloric effects of A2FeMoO6 double perovskites will also be discussed.

scholarly journals STATE OFCoANDMnIN HALF-METALLIC FERROMAGNETCo2MnSiEXPLORED BY MAGNETIC CIRCULAR DICHROISM IN HARD X-RAY PHOTOELECTRON EMISSION AND SOFT X-RAY ABSORPTION SPECTROSCOPIES

SPIN ◽  
2014 ◽  
Vol 04 (04) ◽  
pp. 1440017 ◽  
Author(s):  
GERHARD H. FECHER ◽  
DANIEL EBKE ◽  
SIHAM OUARDI ◽  
STEFANO AGRESTINI ◽  
CHANG-YANG KUO ◽  
...  
Keyword(s):  
Magnetic Moment ◽  
Magnetic Circular Dichroism ◽  
Magnetic Moments ◽  
Magnetic Behavior ◽  
Photoelectron Spectra ◽  
X Rays ◽  
Half Metallic ◽  
X Ray ◽  
Magnetic Dichroism ◽  
X Ray Absorption

The half-metallic Heusler compound Co2MnSi is a very attractive material for spintronic devices because it exhibits very high tunnelling magnetoresistance ratios. This work reports on a spectroscopic investigation of thin Co2MnSi films as they are used as electrodes in magnetic tunnel junctions. The investigated films exhibit a remanent in-plane magnetization with a magnetic moment of about 5 μBwhen saturated, as expected. The low coercive field of only 4 mT indicates soft magnetic behavior. Magnetic dichroism in emission and absorption was measured at the Co and Mn  2p core levels. The photoelectron spectra were excited by circularly polarized hard X-rays with an energy of 6 keV and taken from the remanently magnetized film. The soft X-ray absorption spectra were taken in an induction field of 4 T. Both methods yielded large dichroism effects. An analysis reveals the localized character of the electrons and magnetic moments attributed to the Mn atoms, whereas the electrons related to the Co atoms contribute an itinerant part to the total magnetic moment.

Investigation of Possible Half-Metallic Antiferromagnets on Double Perovskites A2BB′O6 (A=Ca, Sr Ba; B,B′=Transition Metal Elements)

2013 ◽  
Vol 13 (2) ◽  
pp. 526-539 ◽  
Author(s):  
S. H. Chen ◽  
Z. R. Xiao ◽  
Y. P. Liu ◽  
Y. K. Wang
Keyword(s):  
Transition Metal ◽  
Double Exchange ◽  
Correlation Effect ◽  
Orbit Coupling ◽  
Experimental Confirmation ◽  
Double Perovskites ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Transition Elements ◽  
Half Metallic

AbstractA search was made for possible half-metallic (HM) antiferromagnet (AFM) in all the double perovskites structures of Sr2BB'O6 where BB' pairs are any combination of 3d, 4d or 5d transition elements with the exception of La. Sr can also be replaced by Ca or Ba whenever HM-AFM was found and similar calculations were then performed in order to probe further possibilities. It was found that A2MoOsO6, A2TcReO6, A2CrRuO6, where A=Ca, Sr, Ba, are all potential candidates for HM-AFM. The AFM of A2BB'O6 comes from both the superexchange mechanism and the generalized double exchange mechanism via the B(t2g)-O2pπ-B'(t2g) coupling, With the latter also being the origin of their HM. Also considered were the effects of spin-orbit coupling (SOC) and correlation (+U) by introducing +SOC and +U corrections. It is found that the SOC effect has much less influence than the correlation effect on the HM property of the compounds. For A2TcReO6 and A2CrRuO6, after +U, they become nearly Mott-Insulators. In the future, it is hoped that there will be further experimental confirmation for these possible HM-AFM candidates.

Half-metallicity and optoelectronic properties of V-doped zincblende ZnS and CdS alloys

2016 ◽  
Vol 30 (08) ◽  
pp. 1650034 ◽  
Author(s):  
Mohammed El Amine Monir ◽  
H. Baltache ◽  
R. Khenata ◽  
G. Murtaza ◽  
R. Ahmed ◽  
...  
Keyword(s):  
Magnetic Moment ◽  
Density Functional ◽  
Spin Exchange ◽  
Electronic Band Structure ◽  
Magnetic Behavior ◽  
Full Potential ◽  
Generalized Gradient ◽  
Half Metallicity ◽  
Electronic Band ◽  
Half Metallic

In this paper, spin-polarized density functional calculations on the structural, electronic, optical and magnetic properties of the zincblende structure of the [Formula: see text] and [Formula: see text] alloys at [Formula: see text] in the ferromagnetic (FM) ordering has been investigated. The study is accomplished using the full-potential (FP) linearized augmented plane wave plus local orbital (LAPW[Formula: see text]lo) self-consistent scheme of calculations. To incorporate the exchange correlation component in the total energy calculations of the crystal, Perdew–Burke and Ernzerhof (PBE) parameterization for the generalized gradient approximation (GGA) and GGA[Formula: see text]U are employed. Basically, for both alloys, to address their structural properties, we calculated their equilibrium lattice constants, bulk moduli as well as pressure derivatives. In general, from the analysis of the obtained electronic band structure of these alloys, the half-metallic nature of [Formula: see text] and nearly half-metallic nature of the [Formula: see text] alloy are demonstrated. The plotted density of states (DOS) curves project spin-exchange splitting energy [Formula: see text] and [Formula: see text] as generated by V-3d states. It has been clearly evident that the effective potential results for the spin-down case are more striking than for the spin-up case. In order to describe the magnetic behavior of these alloys, the exchange constants [Formula: see text] (valence band) and [Formula: see text] (conduction band) as well as the magnetic moment values are estimated. The calculated results of the magnetic moment show that the main source in the reduction of the local magnetic moment of V in the alloys in comparison with its free value is a [Formula: see text]–[Formula: see text] orbital hybridization and partial transfer to nonmagnetic sites of (Zn, S) and (Cd, S) in [Formula: see text] and [Formula: see text] alloys. In addition, a study concerning optical properties, such as the refractive index, reflectivity and absorption coefficients is performed to determine their potential for optical and optoelectronic devices.

scholarly journals Half-metallic Ferromagnetism in Non-magnetic Double Perovskite Oxides Sr2MSbO6 (M=Al, Ga) Doped with C and N.

2021 ◽  
Author(s):  
AMRANI Bouhalouane ◽  
Djilali BENDJEBBOUR ◽  
Tayeb SEDDIK ◽  
Mohamed Walid MOHAMED ◽  
driss khdoja
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Double Perovskite ◽  
Perovskite Oxides ◽  
Full Potential ◽  
Double Perovskites ◽  
Generalized Gradient ◽  
Half Metallic ◽  
Impurity Bands ◽  
C And N

Abstract Double perovskite oxides have gained tremendous attention in material science and device technology due to their facile synthesis and exceptional physical properties. In this paper, we elucidate the origin of magnetization in non magnetic double perovskite oxides Sr2MSbO6 (M=Al, Ga) induced by non-magnetic 2p-impurities (C and N) substituted. The calculations were done within the full potential linearized augmented plane wave method (FP-LAPW) in the framework of the density functional theory (DFT). The exchange-correlation potential is evaluated using the generalized gradient approximation (GGA) of Perdew–Burke–Ernzerhof (PBE) and the modified Becke and Johnson (mBJ-GGA). Regarding structural properties of undoped double perovskites Sr2MSbO6 (M=Al, Ga), we found that the lattice constants and oxygen positions are in rational accord with the experimental results. Furthermore, both of the examined compounds are brittle in nature with isotropic character. For Sr2AlSbO6 we have got the values of energy gap equal to 1.9 eV and 3.7 eV within the GGA and the mBJ-GGA, respectively. However for Sr2GaSbO6 the values of energy gap obtained in GGA and mBJ-GGA are equal to 0.8 eV and 2.9 eV, respectively. Finally, spin-polarized calculations reveal that the doping C and N can lead to drastic changes in the magneto-electronic properties of the semiconducting Sr2MSbO6 matrix with the integer magnetic moment of 6.00 µB and exhibit half-metallic properties. The origin of ferromagnetism can be attributed to the spin–split impurity bands inside the energy gap of the semiconducting Sr2MSbO6 matrix. These results may help experimentalists in synthesizing new double perovskites for spintronic applications.

scholarly journals Predictive study of ferromagnetism and antiferromagnetism coexistence in Ba1-xGdxRuO3 induced by Gd-doping

2021 ◽  
Vol 67 (6 Nov-Dec) ◽  
Author(s):  
ABBES LABDELLI ◽  
N. Hamdad
Keyword(s):  
Magnetic Moment ◽  
A Priori ◽  
Magnetic Behavior ◽  
Double Perovskite ◽  
Orthorhombic Phase ◽  
Cubic Phase ◽  
Orbital Ordering ◽  
Generalized Gradient ◽  
Two Phases ◽  
Predictive Study

Some ferromagnetic alloys which adopt the perovskite or double-perovskite structure exhibit some remarkable properties, such as electromagnetic effects, charge and orbital ordering, i.e., dielectric and magnetoresistance effects in the same time. These phenomena are related to both electrical conductivity and spin orbit orientation. In order to optimize and explore the structural, magnetic and electronic properties of GdxBa1-xRuO3 alloy, we investigated here the first-principles calculations using the generalized gradient approximation (GGA+U+SO) as implemented in the Wien2K package. The concentration classification of GdxBa1-xRuO3 alloy with (x = 0, 0.125, 0.25, 0.5, 0.875, 1) is given. In this work, we have identified features such transition phases, spin ordered and charge conduction that enable a priori of both crystal structure and magnetic behavior prediction.Our considerable GdxBa1-xRuO3 alloy is a half-metallic in the cubic phase, and, Mott insulator for x=0.875 and semiconductor for x=1 in the orthorhombic phase. The GdxBa1-xRuO3 alloy therefore undergoes a transition between a cubic phase and another orthorhombic at x = 0.5. It is clear that at this point our alloy (Gd0.5Ba0.5RuO3) is at the same time FM and AFM A-type, in another way, we can say that A-AFM and FM configurations coexist in our alloys. In the case of our GdxBa1-xRuO3 alloy, we can see that the total magnetic moment increases linearly with the concentrations "x" since it has passed from 15.99 μB for x = 0 to 39.95 μB for x = 0.5, this is valid in the cubic phase. That is related to a heavily magnetic moment of spin in the Ru atom which increases also linearly with increasing x, while the magnetic moment of Gd decreases slightly. In the orthorhombic phase, its value remains zero regardless of the concentration because we are in an antiferromagnetic (AF) configuration. The collaboration of the 3d-Ru and 2p-O states is suggested to play an important role for the ferromagnetism in the considered alloy. These orbitals were the most regular in the two bands respectively: the conduction band and the valence band in the two phases given here (cubic and orthorhombic). We also note the mixed collaboration of the states 3d-Ba. On the other hand, the contribution of 3d-Gd states was only effective in the band of conduction, at the time when that of the 4f-Gd states was noticed especially in the orthorhombic phase.

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