Magnetization-steps in Y2CoMnO6 double perovskite: The role of antisite disorder
24 Sep 2014-Journal of Applied Physics (AIP Publishing LLCAIP Publishing)-Vol. 116, Iss: 12, pp 123907
TL;DR: In this paper, a paramagnetic-ferromagnetic phase transition occurs in the double perovskite Y2CoMnO6 which has been recently identified as a multiferroic.
Abstract: Antisite disorder is observed to have significant impact on the magnetic properties of the double perovskite Y2CoMnO6 which has been recently identified as a multiferroic. A paramagnetic-ferromagnetic phase transition occurs in this material at Tc ≈ 75 K. At 2 K, it displays a strong ferromagnetic hysteresis with a significant coercive field of Hc ≈ 15 kOe. Sharp steps are observed in the hysteresis curves recorded below 8 K. In the temperature range 2 K ≤ T ≤ 5 K, the hysteresis loops are anomalous as the virgin curve lies outside the main loop. The field-cooling conditions as well as the rate of field-sweep are found to influence the steps. Quantitative analysis of the neutron diffraction data shows that at room temperature, Y2CoMnO6 consists of 62% of monoclinic P21/n with nearly 70% antisite disorder and 38% Pnma. The bond valence sums indicate the presence of other valence states for Co and Mn which arise from disorder. We explain the origin of steps by using a model for pinning of magnetization at the antiphase boundaries created by antisite disorder. The steps in magnetization closely resemble the martensitic transformations found in intermetallics and display first-order characteristics as revealed in the Arrott's plots.
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TL;DR: The structural, magnetic, electrical and dielectric properties of an Ir-based double perovskite compound, La2CoIrO6, have been investigated and it is shown that a clear magnetodielectric coupling effect exists in La2 coirO6 at low temperatures.
Abstract: The structural, magnetic, electrical and dielectric properties of an Ir-based double perovskite compound, La2CoIrO6, have been investigated. The sample undergoes a paramagnetic-ferromagnetic transition at TC, followed by a reentrant spin-glass transition at lower temperatures. The reentrant spin glass state in La2CoIrO6 is associated with the competitions of the antiferromagnetic coupling between Ir4+ and Co2+ ions and the ferromagnetic clusters. La2CoIrO6 shows a semiconducting transport behavior in the temperature range 65 to 360 K and the transport behavior can be well described by the three-dimensional Mott variable range hopping conduction mechanism. Moreover, a strong frequency dependence of dielectric constant behavior for La2CoIrO6 is observed and the dielectric relaxation can be ascribed to the electron hopping between different transition metal ions. In addition, the isothermal magnetic field dependent dielectric constant measurements show that a clear magnetodielectric coupling effect exists in La2CoIrO6 at low temperatures.
35 citations
TL;DR: The structural and magnetic properties of polycrystalline Nd2NiMnO6 (NNMO) synthesized by solid state reaction method have been investigated in this article.
34 citations
TL;DR: In this paper, a polycrystalline sample of a double perovskite crystal structure of a ferrimagnetic oxide with three different magnetic ions was used to investigate its magnetization reversal and inverse hysteresis loop.
Abstract: ${\mathrm{Er}}_{2}{\mathrm{CoMnO}}_{6}$ is a ferrimagnetic oxide consisting of both $4f$ and $3d$ magnetic ions in a monoclinic double perovskite crystal structure (space group $P{2}_{1}/n$) The present work probes some novel magnetic features associated with its ferrimagnetic state on a polycrystalline sample of ${\mathrm{Er}}_{2}{\mathrm{CoMnO}}_{6}$ A clear low temperature compensation point followed by negative magnetization is observed in the field-cooled state of the sample The sample shows a large field-induced change in entropy at very low temperature, which is related to the observed metamagnetism Interestingly, ${\mathrm{Er}}_{2}{\mathrm{CoMnO}}_{6}$ is found to show remarkable feature of inverse hysteresis loop which is quite rare among bulk ferrimagnets Presence of three different magnetic ions, with $4f$ moment of Er having larger uniaxial anisotropy, is likely to be responsible for the observed magnetization reversal and inverse hysteresis loop The sample also shows inverse exchange bias effect, which is presumably related to the negative exchange interaction at the interface of ordered and antisite disordered ferrimagnetic phases Such antisite disorder is quite common among the metal oxides having double perovskite structure
33 citations
TL;DR: In this paper, the double perovskite Yb2CoMnO6 has been synthesized with an almost perfect checkerboard arrangement of Co2+ and Mn4+ cations in the B-sublattice.
Abstract: The double perovskite Yb2CoMnO6 has been synthesized with an almost perfect checkerboard arrangement of Co2+ and Mn4+ cations in the B-sublattice of the perovskite cell. It presents an anomaly in the electric capacitance and a strong magneto-dielectric effect at about 40 K whose interplay with the microscopic magnetic behavior has been investigated by means of neutron diffraction, magnetization, pyroelectric, and relative dielectric permittivity measurements. We show that the onset of an E-type antiferromagnetic ordering of Co2+ and Mn4+ moments monitored by neutron diffraction provokes the noticeable jump of the relative dielectric permittivity (∼9%) at about 40 K. It is also shown that this jump can be totally suppressed by application of a magnetic field of μ0H = 5 T. Neutron experiments and magnetic measurements confirm that such a suppression leading to a significant magneto-dielectric effect is driven by a metamagnetic phase transition from the peculiar E-type ordering of 3d moments into a collinear...
26 citations
TL;DR: In this article, the spin-phonon coupling in rare-earth based manganites with double perovskite structure plays a crucial role in the magnetoelectric properties of these ferromagnetic materials.
25 citations
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