Tiny cause with huge impact: polar instability through strong magneto-electric-elastic coupling in bulk EuTiO₃

Abstract

EuTiO3 exhibits strong magneto-electric coupling at the onset of antiferromagnetic order below TN = 5.7 K. The dielectric permittivity drops at TN by 7% and recovers to normal values with increasing magnetic field. This effect is shown to stem from tiny lattice effects as seen in magnetostriction data which directly affect the soft optic mode and its polarizability coordinate. By combining experimental results with theory we show that marginal changes in the lattice parameter of the order of 0.01% have a more than 1000% effect on the transverse optic soft mode of ETO and thus easily induce a ferroelectric instability.

Large adiabatic temperature and magnetic entropy changes inEuTiO3

“…We also plotted the inverse susceptibility 1/χ dc on the right y axis over a broad temperature range (T = 400−2 K) and it follows the Curie-Weiss (CW) law χ = C/(T −θ cw ). A linear fit to high temperature yields a Curie constant (C = 7.73 emuK/mol Oe) and a positive Curie-Weiss temperature θ CW = 3.1 K. The value of θ CW is consistent with the previously reported result [13]. The effective moment estimated from the relation P eff = ( lowering temperature from 300 K, two prominent anomalies occur, one near room temperature and another below 10 K, as shown in the lower and upper insets.…”

“…In this context, EuTiO 3 is interesting since it has a divalent Eu ion with a large magnetic moment and a tetravalent Ti ion with no magnetic moment. EuTiO 3 , a G-type antiferromagnet below T N = 5.5 ± 0.2K [8,9], has attracted much attention in recent years due to the observations of a magnetodielectric effect in single crystals [10], tensile strain-induced ferromagnetism and ferroelectricity in thin films [11], and magnetoelastic properties [12,13]. It is also unique among the rare earth titanates (RTiO 3 , where R is the rare earth ion) because only the Eu 2+ ion adopts a divalent state instead of a trivalent state that is adopted by other rare earth ions (R = Gd,Y, etc.).…”

Magnetic structure, magnetoelastic coupling, and thermal properties ofEuCrO3nanopowders

“…The linear thermal expansion of a sample of 0.801(1) mm length was measured using a high-resolution miniature dilatometer. [19][20][21][22] The Raman spectra were collected on a Jobin Yvon Typ V 010 LabRAM single grating spectrometer with ∼1 cm −1 spectral resolution. The spectrometer setup included a double super razor edge filter, Peltier cooled CCD camera and a Mikrocryo cryostat with a copper cold finger.…”

A series of new layered lithium europium(II) oxoniobates(V) and -tantalates(V)

“…It becomes antiferromagnetic below T = 5.7 K. The respective phase transition is accompanied by a drop in the dielectric constant, owing to a strong spinlattice coupling [9], and therefore a magnetostriction effect is observed at low temperatures [10]. In addition, the development of 2D magneto-optical devices based on EuTiO 3 [11] appears possible. A common occupation of the A site by Sr 2+ and Eu 2+ leads to an interesting diluted magnetic system in the series Eu x Sr 1−x TiO 3 [12].…”