Effects of different annealing atmospheres on magnetic properties in La2CoMnO6 single crystals

Kim, M.K.; Moon, Joon-Ho; Choi, Heekyung; Oh, Sung‐Yong; Lee, N.; Choi, Young Jai

doi:10.1016/j.cap.2015.04.009

Cited by 18 publications

(9 citation statements)

References 33 publications

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“…Double perovskite R 2 CoMnO 6 (R = La, …, Lu) compounds, where Co 2+ and Mn 4+ ions are alternately located in corner-shared octahedral environments, exhibit assorted physical properties such as metamagnetism 15–17 , exchange bias 18,19 , the re-entrant spin-glass state 20,21 , and multiferroicity 16,22–24 because of the intricate magnetic interactions and ionic valence/antisite disorders between mixed-valence magnetic ions. The ferromagnetic order originates from the dominant Co 2+ and Mn 4+ superexchange interactions, and its transition temperature varies linearly from 204 K for La 2 CoMnO 6 25 to 48 K for Lu 2 CoMnO 6 26 as the size of the rare earth ions decreases. GCMO crystallizes in a monoclinic P2 1 /n double-perovskite structure with a unit cell of a = 5.3158 Å, b = 5.6050 Å, c = 7.5759 Å, and β = 89.9541°.…”

Section: Introductionmentioning

confidence: 99%

Giant Anisotropic Magnetocaloric Effect in Double-perovskite Gd2CoMnO6 Single Crystals

Moon

Kim

Choi

et al. 2017

Sci Rep

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The magnetocaloric effect (MCE) is described by the change in temperature of a material by magnetic field variation and is a crucial subject in magnetism; it is motivated by the desire to enhance energy-efficient magnetic refrigeration for clean technology. Despite the recent discovery of the giant cryogenic MCE in double perovskites, the role of magnetic anisotropy has not yet been clearly discussed, because of the averaging effect of polycrystalline samples. Here, we investigated the anisotropic MCE in the single-crystal double perovskite Gd2CoMnO6. In addition to the ferromagnetic order of the Co2+ and Mn4+ moments, the large Gd3+ moments align below T Gd = 21 K, exhibiting an isotropic nature. Because of the intricate temperature development of magnetically hysteretic behaviour and metamagnetism, the change in magnetic entropy along the c-axis appears to be relatively small. On the contrary, the smaller but almost reversible magnetization perpendicular to the c-axis leads to a large MCE with a maximum entropy change of 25.4 J/kg·K. The anisotropic MCE generates a giant rotational MCE, estimated as 16.6 J/kg·K. Our results demonstrate the importance of magnetic anisotropy for understanding the MCE and reveal essential clues for exploring suitable magnetic refrigerant compounds aiming at magnetic functional applications.

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Section: Introductionmentioning

confidence: 99%

Giant Anisotropic Magnetocaloric Effect in Double-perovskite Gd2CoMnO6 Single Crystals

Moon

Kim

Choi

et al. 2017

Sci Rep

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“…Annealing of oxide ceramics in different ambient conditions such as nitrogen, oxygen and air has also been a widely adopted choice to tune their electrical, optical and magnetic properties . Depending on the nature of ambient whether oxidative or reductive, the oxygen vacancy concentration in the material can be significantly altered which is manifested in the changes in dielectric behavior as observed for Bi:SrTiO 3 , PZN–PLZT, SrBi 2 Ta 2 O 9 , and YMnO 3.…”

Section: Introductionmentioning

confidence: 99%

Effect of annealing atmosphere on leakage and dielectric characteristics of multiferroic gallium ferrite

et al. 2017

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Mutliferroic and magnetoelectric gallium ferrite (GaFeO 3 ) is plagued by substantial electrical leakage in polycrystalline form. Here, we report on understanding the conduction mechanism in gallium ferrite ceramic samples vis-a-vis processing conditions. The results show that oxygen annealed samples exhibit minimum electrical leakage as compared to air or nitrogen annealed samples suggesting the role of oxy3gen vacancies on electrical conduction. Detailed time and temperaturedependent impedance spectroscopy analysis of the samples showed higher activation energy of conduction in oxygen annealed samples than in air or nitrogen annealed samples. The lower activation energies of 0.3-0.4 eV in nitrogen/air annealed samples were attributed to higher oxygen vacancy concentration while oxygen annealed samples with low oxygen vacancy concentration exhibited higher activation energy of~0.50 eV (high frequency, i.e., grain) and 0.98 eV (low frequency, i.e., grain boundary), latter due to superior level of oxygenation at the grain boundaries. Further, X-ray photoelectron spectroscopy revealed that the oxygen vacancies are compensated by the valence fluctuation between Fe 2+ / Fe 3+ ions whose extent is higher in air/nitrogen annealed samples than in oxygen annealed samples. The conduction mechanisms that could be active are most likely to be double ionization of oxygen vacancies and hopping from Fe 2+ to Fe 3+ states, latter especially in oxygen deficient samples.

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“…Whereas T C1 value of pure LCMO oxides are lower and ranges from 210 K to 235 K for polycrystalline samples [35][36][37][38] and thin films [39,42]. Obviously, and is attributed to the short-range magnetic ordering of Mn 4+ -O -Ni 2+ [32,34,31].…”

Section: The Magnetic Properties Studiesmentioning

confidence: 99%

The effect of cation disorder on magnetic properties of new double perovskites La2Ni Co1-MnO6 (x = 0.2–0.8)

Harbi

Moutaabbid

et al. 2019

Journal of Alloys and Compounds

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Effects of different annealing atmospheres on magnetic properties in La2CoMnO6 single crystals

Cited by 18 publications

References 33 publications

Giant Anisotropic Magnetocaloric Effect in Double-perovskite Gd2CoMnO6 Single Crystals

Giant Anisotropic Magnetocaloric Effect in Double-perovskite Gd2CoMnO6 Single Crystals

Effect of annealing atmosphere on leakage and dielectric characteristics of multiferroic gallium ferrite

The effect of cation disorder on magnetic properties of new double perovskites La2Ni Co1-MnO6 (x = 0.2–0.8)

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