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Szytula A.,Jagiellonian University | Penca B.,Jagiellonian University | Dyakonov V.,Polish Academy of Sciences | Dyakonov V.,Aa Galkin Donetsk Physico Technical Institute | And 2 more authors.
Acta Physica Polonica A | Year: 2014

The neutron powder diffraction (NPD) measurements of the nano-size DyMnO3 manganite have been performed. The obtained results indicate that this compound crystallizes in the orthorhombic crystal structure described by the space group Pnma. The Mn and Dy moments order antiferromagnetically at different temperatures and form modulated magnetic structure described by the propagation vector κ = (κx; 0; 0) with the different values of κx component for the Mn and Dy sublattices. The values of κx component for Mn sublattice increase with decreasing of the temperature and are smaller that in bulk compound. The wide Bragg peaks related to the Dy sublattice suggest that the magnetic order in this sublattice has the cluster-like character. Source


Jaworska-Golab T.,Jagiellonian University | Baran S.,Jagiellonian University | Duraj R.,Cracow University of Technology | Marzec M.,Jagiellonian University | And 6 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2015

Investigations of structural and magnetic phase transitions in the NiMn0.89Cr0.11Ge half-Heusler alloy were carried out by DSC, XRD (80-400 K), magnetic susceptibility and magnetization (1.9-400 K, magnetic field up to 9.0 T, pressure up to 5.25 kbar) measurements. At high temperatures the sample is a single phase crystallizing in the hexagonal crystal structure (Ni2In-type, space group P63/mmc) while below 260 K, down to 100 K, some amount of the hexagonal phase coexists with the orthorhombic (TiNiSi-type, space group Pnma) one. Strong magnetostructural coupling is observed. Magnetic data indicate that with increasing temperature magnetic properties of the sample change from antiferro- to ferro- and then to paramagnetic ones. The latter magnetic phase transition is associated with the crystal structure change and results in large magnetic entropy change equal to -51 J/kg K at μ0H= 9.0 T near 260 K. Application of external pressure shifts TC towards lower temperatures. © 2015 Elsevier B.V. All rights reserved. Source


Prokhorov A.D.,Aa Galkin Donetsk Physico Technical Institute | Prokhorov A.A.,Aa Galkin Donetsk Physico Technical Institute | Chernysh L.F.,Aa Galkin Donetsk Physico Technical Institute | Dyakonov V.P.,Aa Galkin Donetsk Physico Technical Institute | And 2 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2011

The ground state of Gd3 ions substituting for trivalent europium in the EuAl3(BO3)4 single crystal was studied by electron paramagnetic resonance (EPR) over the temperature range of 3004.2 K and at pressures up to 9 kbar. The EPR spectra were analysed using the spin Hamiltonian of axial symmetry. The following parameters are reported: g=1.981±0.002, b2 0=280.18±0.12, b 4 0=-12.95±0.08 and b6 0=0.61±0.12 (at T=298 K). The distortions of the nearest environment of Gd3 ion were analysed within the framework of the superposition model of crystal field. © 2011 Published by Elsevier B.V. Source


Bazela W.,Cracow University of Technology | Dul M.,Cracow University of Technology | Dyakonov V.,Polish Academy of Sciences | Dyakonov V.,Aa Galkin Donetsk Physico Technical Institute | And 8 more authors.
Acta Physica Polonica A | Year: 2012

The magnetic properties including magnetic structure of poly and nano samples of TbMnO 3 are determined. All the samples investigated are antiferromagnets. In these samples the Mn ad Tb moments order antiferromag-netically at different temperatures and form modulated magnetic structure described by the propagation vector κ=(κ x,0,0) with different value of κ x for the Mn and Tb sublattices. Comparison of the data for poly and nano samples indicates the decrease of the moment and increase of the κ x component of propagation vector in the nano specimens. The wide Bragg peak related to the Tb sublattice suggests that the magnetic order has the claster-like character. The magnetic moments value in both sublattices is smaller, whereas the κ x values are larger for nano samples. Source


Stognij A.,Scientific Practical Materials Research Center of Belarus | Novitskii N.,Scientific Practical Materials Research Center of Belarus | Sazanovich A.,Polish Academy of Sciences | Poddubnaya N.,Scientific Practical Materials Research Center of Belarus | And 6 more authors.
EPJ Applied Physics | Year: 2013

Magnetoelectric properties of layered heterostructures (FM/PZT/FM) n (n≤3) obtained by ion-beam sputtering deposition of ferromagnetic metal (FM), where FM is the cobalt (Co) or permalloy Ni 78Fe22, onto ferroelectric ceramic based on lead zirconate titanate (PZT) have been studied. The polished ferroelectric plates in thickness from 400 to 20 Im were subjected to finished treatment by ion-beam sputtering. After plasma activation they were covered by the ferromagnetic films from 1 to 6 Im in thickness. Enhanced characteristics of these structures were reached by means of both the thickness optimization of ferroelectric and ferromagnetic layers and obtaining of ferromagnetic/ferroelectric interfaces being free from defects and foreign impurities. Assuming on the basis of analysis of elastic stresses in the ferromagnetic film that the magnetoelectric effect forms within ferromagnetic/ferroelectric interface, the structures with 2a3 ferromagnetic layers were obtained. In layered heterostructure (Py/PZT/Py)3, the optimal thickness of ferromagnetic film was 2 Im, and outer and inner ferroelectric layers had 20 Im and 80 Im in thickness, respectively. For such structure the maximal magnetoelectric voltage coefficient of 250 mV/(cm Oe) was reached at a frequency 100 Hz in magnetic field of 0.25 T at room temperature. The structures studied can serve as energy-independent elements detecting the change of magnetic or electric fields in electronic devices based on magnetoelectric effect. © EDP Sciences, 2013. Source

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