Magnetic resonance study of bulk and thin film EuTiO3

článek v časopise ve Web of Science, Jimp

angličtina

Magnetic resonance spectra of EuTiO3 in both bulk and thin film form were taken at temperatures from 3–350 K and microwave frequencies from 9.2–9.8 and 34 GHz. In the paramagnetic phase, magnetic resonance spectra are determined by magnetic dipole and exchange interactions between Eu2+ spins. In the film, a large contribution arises from the demagnetization field. From detailed analysis of the linewidth and its temperature dependence, the parameters of spin–spin interactions were determined: the exchange frequency is 10.5 GHz and the estimated critical exponent of the spin correlation length is ≈0.4. In the bulk samples, the spectra exhibited a distinct minimum in the linewidth at the Néel temperature, TN ≈ 5.5 K, while the resonance field practically does not change even on cooling below TN. This is indicative of a small magnetic anisotropy ~320 G in the antiferromagnetic phase. In the film, the magnetic resonance spectrum is split below TN into several components due to excitation of the magnetostatic modes, corresponding to a non-uniform precession of magnetization. Moreover, the film was observed to degrade over two years. This was manifested by an increase of defects and a change in the domain structure. The saturated magnetization in the film, estimated from the magnetic resonance spectrum, was about 900 emu cm−3 or 5.5 μB/unit cell at T = 3.5 K.

multiferroic, phase transition, electron paramagnetic resonance, antiferromagnetic

LAGUTA, V.; KAMBA, S.; MARYŠKO, M.; ANDRZEJEWSKI, B.; KACHLÍK, M.; MACA, K.; LEE, J.; SCHLOM, D.

15. 3. 2017

0953-8984

Journal of Physics: Condensed Matter

29

10

Spojené království Velké Británie a Severního Irska

105401-1

105401-9

9