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Journal ArticleDOI

Magnetization-steps in Y2CoMnO6 double perovskite: The role of antisite disorder

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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Citations
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Journal ArticleDOI
TL;DR: The maximum sensor sensitivity of Y2MgTiO6:Mn4+ is determined to be as high as 0.001 42 K-1 at 153 K, which demonstrates potential applications for the optical thermometry at low-temperature environments.
Abstract: Mn4+-doped Y2MgTiO6 phosphors are synthesized by the traditional solid-state method. Powder X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectrometer are employed to...

138 citations

Journal ArticleDOI
TL;DR: The role of antisite disorder in creating the domain structure leading to exchange bias effect is highlighted in this article, where a model based on growth of ferromagnetic domains overcoming the elastic energy of structurally pinned magnetic interfaces, which closely resembles martensitic-like transitions, is adapted to explain the observed effects.
Abstract: Exchange bias effect in the ferromagnetic double perovskite compound Y2CoMnO6, which is also a multiferroic, is reported. The exchange bias, observed below 8 K, is explained as arising due to the interface effect between the ferromagnetic and antiferromagnetic clusters created by antisite disorder in this material. Below 8 K, prominent ferromagnetic hysteresis with metamagnetic “steps” and significant coercive field, Hc ≈ 10 kOe are observed in this compound which has a Tc ≈ 75 K. A model based on growth of ferromagnetic domains overcoming the elastic energy of structurally pinned magnetic interfaces, which closely resembles martensitic-like transitions, is adapted to explain the observed effects. The role of antisite disorder in creating the domain structure leading to exchange bias effect is highlighted in the present work.

47 citations

Journal ArticleDOI
TL;DR: In this article, the influence of rare earth site substitution on structural, transport and magnetic characteristics of polycrystalline Ln2CoMnO6 (Ln= La, Sm and Gd) has been systematically investigated in details.

41 citations

Journal ArticleDOI
TL;DR: The role of antisite disorder in creating the domain structure leading to exchange bias effect is highlighted in this paper, where a model based on growth of ferromagnetic domains overcoming the elastic energy of structurally pinned magnetic interfaces, which closely resembles martensitic-like transitions, is adapted to explain the observed effects.
Abstract: Exchange bias effect in the ferromagnetic double perovskite compound Y$_2$CoMnO$_6$, which is also a multiferroic, is reported. The exchange bias, observed below 8~K, is explained as arising due to the interface effect between the ferromagnetic and antiferromagnetic clusters created by {\it antisite} disorder in this material. Below 8~K, prominent ferromagnetic hysteresis with metamagnetic "steps" and significant coercive field, $H_c \approx$ 10~kOe are observed in this compound which has a $T_c \approx$ 75~K. A model based on growth of ferromagnetic domains overcoming the elastic energy of structurally pinned magnetic interfaces, which closely resembles martensitic-like transitions, is adapted to explain the observed effects. The role of {\it antisite} disorder in creating the domain structure leading to exchange bias effect is highlighted in the present work.

40 citations

Journal ArticleDOI
TL;DR: Magnetic and dielectric properties of the double perovskite Ho2NiMnO6 are reported and signs of inherent Griffiths phase pertaining to the Ni/Mn subsystem are visible.
Abstract: Magnetic and dielectric properties of the double perovskite Ho2NiMnO6 are reported. The compound is synthesized by nitrate route and is found to crystallize in monoclinic P2(1)/n space group. Lattice parameters obtained by refining powder x-ray diffraction data are; a = 5.218(2)angstrom, b = 5.543(2)angstrom, c = 7.480(3)angstrom and the monoclinic angle i beta = 90.18 degrees(4). A phase transition is observed at T-C = 86 K in the temperature-dependent magnetization curve, M(T). The inverse magnetic susceptibility, (1/chi(T)) fits reasonably well with modified Curie-Weiss law by incorporating the paramagnetic response of Ho3+. 1/chi(T) manifests as an upward deviation from ideal Curie-Weiss behaviour well above the ferromagnetic transition. Signs of inherent Griffiths phase pertaining to the Ni/Mn subsystem are visible when one subtracts the Ho3+ paramagnetic contribution from total susceptibility and does the power-law analysis. The magnetic hysteresis at 2 K gives the maximum value of magnetization M-max approximate to 15 mu(B)/f. u. at 50 kOe. Field-derivative of magnetization at 2 K shows discontinuities which indicates the existence of metamagnetic transitions in this compound. This needs to be probed further. Out of the two dielectric relaxations observed, the one at low temperature may be attributed to phononic frequencies and that at higher temperature may be due to Maxwell-Wagner relaxation. A correlation between magnetic and lattice degrees of freedom is plausible since the anomaly in dielectric constant coincides with T-C.

36 citations

References
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Journal ArticleDOI
TL;DR: In this article, the multiferroic behavior in double perovskite Y2CoMnO6 with ferroelectric transition temperature Tc = 80 K was reported.
Abstract: We report multiferroic behaviour in double perovskite Y2CoMnO6 with ferroelectric transition temperature Tc = 80 K. Both X-ray diffraction and neutron scattering data confirm a centro-symmetric crystal structure of space group P21/n at room temperature. The saturation polarization and magnetization are estimated to be 65 μC/m2 and 6.2 μB/f.u. respectively. The magneto-electric coupling parameter, on the other hand, is small as a 5 T field suppresses the electric polarization by only ∼8%. The origin of ferroelectricity is associated with magnetic ordering of Co2+ and Mn4+ moments in ↑↑-↓↓ arrangement. A model based on exchange-striction is proposed to explain the observed high temperature ferroelectricity.

83 citations

Journal ArticleDOI
TL;DR: In this article, the authors report on peculiar metamagnetic transitions which take place in antiferromagnetic, charge and orbitally ordered manganites at very low temperatures, the virgin magnetization curves of some of these compounds exhibit several, sharp steps giving rise to a staircase-like shape.

78 citations

Journal ArticleDOI
TL;DR: Bond distances clearly show Mn(4+)/Co(2+) valence states in the well-ordered sample, while for the disordered one this picture still holds, and impedance complex plane analyses prove that these phenomena appear at the frequency-temperature region where extrinsic effects dominate the dielectric response.
Abstract: The origin of dielectric anomalies and magnetodielectric response of La2MnCoO6 has been investigated by means of ultra-high resolution synchrotron x-ray powder diffraction, neutron powder diffraction, resistivity, magnetization and dielectric measurements. The study has been performed on two different bulk samples presenting different degrees of Mn/Co order: 95 and 74%. Beside the well-known influence on magnetic properties, our results show that the main effect of disorder lies on the electrical resistivity. Bond distances clearly show Mn4+/Co2+ valence states in the well-ordered sample, while for the disordered one this picture still holds. AC resistivity data show dielectric anomalies and a small magnetodielectric effect, but impedance complex plane analyses prove that these phenomena appear at the frequency–temperature region where extrinsic effects dominate the dielectric response.

74 citations

Journal ArticleDOI
TL;DR: It is shown that the double perovskite (La,Lu)MnNiO6 with Lu concentrations at and below 50% combines polar behavior and ferromagnetism.
Abstract: We elucidate a mechanism for obtaining polar behavior in magnetic perovskites based on A-site disorder and demonstrate this mechanism by density functional calculations for the double perovskite (La, Lu)MnNiO 6 with Lu concentrations at and below 50%. We show that this material combines polar behavior and ferromagnetism. The mechanism is quite general and may be applicable to a wide range of magnetic perovskites.

73 citations

Journal ArticleDOI
TL;DR: In this paper, multiferroic behavior in double perovskite Y2CoMnO6 with ferroelectric transition temperature Tc = 80K was reported.
Abstract: We report multiferroic behavior in double perovskite Y2CoMnO6 with ferroelectric transition temperature Tc = 80K. The origin of ferroelectricity is associated with magnetic ordering of Co2+ and Mn4+ moments in a up-up-down-down arrangement. The saturation polarization and magnetization are estimated to be 65 uC/m2 and 6.2 Bohr magneton/f.u. respectively. The magnetoelectric coupling parameter, on the other hand, is small as a 5 Tesla field suppresses the electric polarization by only ~8%. This is corroborated with observed hysteretic behaviour at 5K that remains unsaturated even upto 7 Tesla. A model based on exchange-striction is proposed to explain the observed high temperature ferroelectricity.

72 citations