Double‐Exchange Magnetic Interactions in High‐Temperature Ferromagnetic Iron Chalcogenide Monolayers

Electron spin resonance spectra of copper phthalocyanine doped with alkaline metals ( A x CuPc ) have been investigated. The temperature dependence of ESR spectra indicates ferromagnetic behavior. The Curie-Weiss temperature varies from 30 to 115 K depending on the stoichiometry x of the samples. Some particles of polycrystalline samples were attracted to a weak magnet at temperatures slightly higher than 77 K. The observed magnetism is caused by unpaired π-electrons of phthalocyanine anions on the eg doubly degenerated molecular orbital. The observed ferromagnetism can be understood within the framework of the McConnell-2 model proposed for organic ferromagnetic charge-transfer complexes. The high-temperature magnetism in A x CuPc is considered to be a result of the Zener mechanism of double exchange between phthalocyanine molecular anions of different valence.

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Incommensurate magnetic structure, Fe/Cu chemical disorder, and magnetic interactions in the high-temperature multiferroicYBaCuFeO5

Physical Review B ◽

10.1103/physrevb.91.064408 ◽

2015 ◽

Vol 91 (6) ◽

Cited By ~ 25

Author(s):

M. Morin ◽

A. Scaramucci ◽

M. Bartkowiak ◽

E. Pomjakushina ◽

G. Deng ◽

...

Keyword(s):

High Temperature ◽

Magnetic Structure ◽

Magnetic Interactions ◽

Incommensurate Magnetic Structure ◽

Chemical Disorder

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High Temperature Superconductivity in an Iron Chalcogenide with a Very Simple Fermi-Surface

10.36471/jccm_april_2012_02 ◽

2012 ◽

Keyword(s):

High Temperature ◽

Fermi Surface ◽

High Temperature Superconductivity ◽

Iron Chalcogenide

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High temperature EPR study of the M3Fe4V6O24 (M = Cu, Zn, Mg and Mn)

Materials Science-Poland ◽

10.1515/msp-2016-0069 ◽

2016 ◽

Vol 34 (3) ◽

pp. 517-522 ◽

Cited By ~ 1

Author(s):

Niko Guskos ◽

Grzegorz Zolnierkiewicz ◽

Janusz Typek ◽

Malwina Pilarska ◽

Constantinos Aidinis ◽

...

Keyword(s):

High Temperature ◽

Resonance Field ◽

Spin Systems ◽

Magnetic Interactions ◽

Paramagnetic Resonance ◽

Integrated Intensity ◽

Epr Parameters ◽

Magnetic Ions ◽

Electron Paramagnetic

AbstractElectron paramagnetic resonance (EPR) spectra of M3Fe4V6O24 (M = Cu, Zn, Mg and Mn) compounds in high temperature range (293 K to 493 K) have been investigated. The role of magnetic (Cu, Mn) and non-magnetic (Zn, Mg) ions in M3Fe4V6O24 structure in formation of magnetic resonance spectra was studied. Temperature dependence of EPR parameters: resonance field, linewidth and integrated intensity were examined. Similarities and differences in temperature behavior of these parameters has been discussed in terms of different relaxation mechanisms and magnetic interactions in the spin systems. An important role of additional magnetic ions (M = Mn or Cu) in the M3Fe4V6O24 structure has been identified and its consequences considered.

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Structure and Magnetic Properties of Aerosol Nanoparticles of Fe and Its Alloys

International Journal of Inorganic Chemistry ◽

10.1155/2012/610305 ◽

2012 ◽

Vol 2012 ◽

pp. 1-43 ◽

Cited By ~ 3

Author(s):

Yu. I. Petrov ◽

E. A. Shafranovsky

Keyword(s):

Magnetic Properties ◽

Fine Structure ◽

High Temperature ◽

Hyperfine Field ◽

Field Distribution ◽

Pure Iron ◽

Bulk Material ◽

Magnetic Interactions ◽

Hyperfine Field Distribution ◽

Aerosol Nanoparticles

Structure and magnetic properties of aerosol nanoparticles of Fe and its alloys (FeMn, FeNi, FeNiMn, FePt, FeCr, FeCo, and FeCu) have been reviewed. It has been shown that, compared to a bulk material, the particles have a number of specific features being of much fundamental and applied interest. The effect of both a quenched high-temperature Fe modification and its oxides on the structure and magnetism of nanoparticles has been considered in detail. Particular attention has been paid to the recently observed fine structure in the hyperfine field distribution at iron nuclei in Mössbauer spectra for pure iron and its alloys both as a bulk and aerosol nanoparticles. This phenomenon makes it possible to reveal very weak magnetic interactions in the system under study. The plausible origin of these magnetic interactions has been also discussed.

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Oxide Dilute Magnetic Semiconductors—Fact or Fiction?

MRS Bulletin ◽

10.1557/mrs2008.225 ◽

2008 ◽

Vol 33 (11) ◽

pp. 1053-1058 ◽

Cited By ~ 137

Author(s):

J.M.D. Coey ◽

S.A. Chambers

Keyword(s):

Thin Films ◽

High Temperature ◽

Magnetic Semiconductors ◽

Bulk Material ◽

Room Temperature Ferromagnetism ◽

Magnetic Moments ◽

Dilute Magnetic Semiconductors ◽

Double Exchange ◽

Secondary Phases ◽

Solid State Mater

AbstractMagnetism in oxides was thought to be well-understood in terms of localized magnetic moments and double-exchange or superexchange rules. This understanding was shaken by the publication of an article in 2001 stating that thin films of anatase TiO2 with only 7 at.% Co substitution had a Curie point in excess of 400 K [Matsumoto et al., Science291, 854 (2001)]. Room-temperature ferromagnetism had previously been predicted for p-type ZnO with 5 at.% Mn [Dietl et al., Science287, 1019 (2000)]. A flood of reports of thin films and nanoparticles of new oxide “dilute magnetic semiconductors” (DMSs) followed, and high-temperature ferromagnetism has been reported for other systems with no 3dcations. The expectation that these materials would find applications in spintronics motivated research in this area. Unfortunately, the data are plagued by instability and a lack of reproducibility. In many cases, the ferromagnetism can be explained by uncontrolled secondary phases; it is absent in well-crystallized films and bulk material. However, it appears that some form of high-temperature ferromagnetism can result from defects present in the oxide films [Coey, Curr. Opin. Solid State Mater. Sci.10, 83 (2007); Chambers, Surf. Sci. Rep.61, 345 (2006)], although they are not DMSs as originally envisaged.

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Development of short and long-range magnetic order in the double perovskite based frustrated triangular lattice antiferromagnet Ba$$_{2}$$MnTeO$$_{6}$$

Scientific Reports ◽

10.1038/s41598-021-84876-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

J. Khatua ◽

T. Arh ◽

Shashi B. Mishra ◽

H. Luetkens ◽

A. Zorko ◽

...

Keyword(s):

Triangular Lattice ◽

Degrees Of Freedom ◽

Spin Dynamics ◽

Muon Spin ◽

Magnetic Ordering ◽

Double Exchange ◽

Double Perovskite ◽

Magnetic Interactions ◽

Spin Frustration ◽

Ordered State

AbstractFrustrated magnets based on oxide double perovskites offer a viable ground wherein competing magnetic interactions, macroscopic ground state degeneracy and complex interplay between emergent degrees of freedom can lead to correlated quantum phenomena with exotic excitations highly relevant for potential technological applications. By local-probe muon spin relaxation ($$\mu$$ μ SR) and complementary thermodynamic measurements accompanied by first-principles calculations, we here demonstrate novel electronic structure and magnetic phases of Ba$$_{2}$$ 2 MnTeO$$_{6}$$ 6 , where Mn$$^{2+}$$ 2 + ions with S = 5/2 spins constitute a perfect triangular lattice. Magnetization results evidence the presence of strong antiferromagnetic interactions between Mn$$^{2+}$$ 2 + spins and a phase transition at $$T_{N}$$ T N = 20 K. Below $$T_{N}$$ T N , the specific heat data show antiferromagnetic magnon excitations with a gap of 1.4 K, which is due to magnetic anisotropy. $$\mu$$ μ SR reveals the presence of static internal fields in the ordered state and short-range spin correlations high above $$T_{N}$$ T N . It further unveils critical slowing-down of spin dynamics at $$T_{N}$$ T N and the persistence of spin dynamics even in the magnetically ordered state. Theoretical studies infer that Heisenberg interactions govern the inter- and intra-layer spin-frustration in this compound. Our results establish that the combined effect of a weak third-nearest-neighbour ferromagnetic inter-layer interaction (owing to double-exchange) and intra-layer interactions stabilizes a three-dimensional magnetic ordering in this frustrated magnet.

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Phase Diagram of Spin States and Magnetic Interactions in Isotope Substituted (Pr,Eu)0.7Ca0.3CoO3

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.168-169.465 ◽

2010 ◽

Vol 168-169 ◽

pp. 465-468

Author(s):

A.V. Kalinov ◽

O.Yu. Gorbenko ◽

A.N. Taldenkov ◽

J. Rohrkamp ◽

O. Heyer ◽

...

Keyword(s):

Phase Diagram ◽

Spin State ◽

Magnetic Ordering ◽

Double Exchange ◽

Magnetic Interactions ◽

First Order ◽

Spin State Transition ◽

Intermediate Spin ◽

Magnetic Spin ◽

The Eu

The magnetic/spin-state phase diagram of the (Pr1-yEuy)0.7Ca0.3CoO3 series was obtained on the basis of measurements of the specific heat, thermal expansion, magnetization and resistivity. The phase diagram reveals three different states depending on the static distortions (Eu content), the oxygen-isotope mass, and the temperature. The samples with the lower Eu concentrations are ferromagnetically ordered up to moderate temperatures (about 50 K),, most probably, due to the low-spin Co4+ – intermediate-spin Co3+ interaction of the double-exchange type. As the Eu doping increases, the Co3+ LS (S = 0) state becomes stabilized and the magnetic ordering of the Co4+ ions is suppressed up to temperatures well below 5 K, resulting in a low-temperature anomaly in Cp. At higher temperatures, we observe a first-order spin-state transition from the LS to the IS state of Co3+, which is accompanied by a decrease in the electrical resistivity, an increase in the magnetization, and a strong lattice expansion.

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