Magnetic and dielectric properties of multiferroic Eu_0.5Ba_0.25Sr_0.25TiO₃ ceramics

Author： Goian Veronica Kamba Stanislav Vaněk Přemysl Savinov Maxim Kadlec Christelle Prokleška Jan

ISSN： 0141-1594

Source： Phase Transitions: A Multinational Journal, Vol.86, Iss.2-3, 2013-02, pp. : 191-199

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Abstract

Dielectric and magnetic properties of Eu_0.5Ba_0.25Sr_0.25TiO₃ are investigated between 10 and 300 K in the frequency range 10 Hz–100 THz. A peak in permittivity revealed near 130 K and observed ferroelectric hysteresis loops prove the ferroelectric order below this temperature. The peak in permittivity is given mainly by softening of the lowest frequency polar phonon (soft mode revealed in THz and infrared (IR) spectra) that demonstrates displacive character of the phase transition. Room-temperature X-ray diffraction analysis reveals cubic structure, but the IR reflectivity spectra give evidence of a lower crystal structure, presumably tetragonal I4/mcm with tilted oxygen octahedra as it has been observed in EuTiO₃. The magnetic measurements show that the antiferromagnetic order occurs below 1.8 K. Eu_0.5Ba_0.25Sr_0.25TiO₃ has three times lower coercive field than Eu_0.5Ba_0.5TiO₃; therefore, we propose this system for measurements of electric dipole moment of electron.