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226 results on '"Pavlikov, V."'

2. Mechanisms of magnetoelectricity in manganese doped incipient ferroelectrics

Author

Kuzian, R. O., Laguta, V. V., Dare, A. -M., Kondakova, I. V., Marysko, M., Raymond, L., Garmash, E. P., Pavlikov, V. N., Tkach, A., Vilarinho, P. M., and Hayn, R.

Subjects
Condensed Matter - Materials Science, Condensed Matter - Strongly Correlated Electrons
Abstract

We report magnetization measurements and magnetic resonance data for SrTiO3 doped by manganese. We show that the recently reported coexistent spin and dipole glass (multiglass) behaviours are strongly affected by the distribution of Mn ions between the Sr and Ti sites. Motivated by this finding we calculate the magnetic interactions between Mn impurities of different kinds. Both LSDA+U and many-body perturbation theory evidence that magnetic and magnetoelectric interactions are mediated by Mn$_B^{4+}$ ions substituting for Ti. We propose two microscopic magnetoelectric coupling mechanisms, which can be involved in all magnetoelectric systems based on incipient ferroelectrics. In the first one, the electric field modifies the spin susceptibility via spin-strain coupling of Mn$_{B}^{4+}$. The second mechanism concerns Mn pairs coupled by the position-dependent exchange interaction., Comment: 6 pages, 2 figures; Revised version, accepted for publication in EPL. The physics underlying the proposed mechanisms is more detailed

Published
2010
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38. Room-temperature ferroelectricity, superparamagnetism and large magnetoelectricity of solid solution PbFe1/2Ta1/2O3 with (PbMg1/3Nb2/3O3)0.7(PbTiO3)0.3.

Author

Glinchuk, M. D., Kuzian, R. O., Zagorodniy, Yu. O., Kondakova, I. V., Pavlikov, V. M., Karpec, M. V., Kulik, M. M., Škapin, S. D., Yurchenko, L. P., and Laguta, V. V.

Subjects
SOLID solutions, FERROELECTRICITY, IRON ions, MAGNETIC measurements, PHASE transitions, MULTIFERROIC materials
Abstract

We report the properties of first synthesized ceramic samples of a perovskite solid solution (PbFe1/2Ta1/2O3)x[(PbMg1/3Nb2/3O3)0.7(PbTiO3)0.3]1−x, x = 0.4, 0.5. The solution is a single-phase material contrary to broadly studied multiphase (magnetic/ferroelectric) composites. Both compounds are ferroelectrics with a diffuse phase transition. An increase in x value results in a decrease in phase transition diffuseness, and an increase in the remnant polarization. 207Pb NMR shows that iron ions are nonuniformly distributed over octahedral sites and tend to random occupation of these sites in the perovskite structure. In particular, the NMR data indicate a tendency to form regions with a higher concentration of iron in the perovskite structure. Magnetic measurements show the coexistence of superparamagnetic and paramagnetic phases in the samples. The paramagnetoelectric (PME) coefficients determined by a dynamic method at room temperature have values β ≈ 0.15 × 10−15 s A−1 (x = 0.4) and 0.54 × 10−15 s A−1 (x = 0.5) at low magnetic fields (± 300 Oe), which are three thousands times larger than that in most single-phase magnetoelectric materials. Our measurements show that the main contribution to the PME response is caused by the superparamagnetic phase. Because the ME response is proportional to dM2/dH, it can be amplified by many orders of magnitude for the multiferroics with the superparamagnetic phase due to a sharp change of magnetization with the field. [ABSTRACT FROM AUTHOR]

Published
2020
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