title: Magnetic resonance study of bulk and thin film EuTiO3.
abstract: Magnetic resonance spectra of EuTiO3in 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 TNinto 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-3or 5.5 µB/unit cell at T  =  3.5 K.
authors.affiliation: Institute of Physics ASCR, Na Slovance 2, 18221 Prague 8, Czechia. Institute of Physics, Opole University, Oleska 48, 45-052 Opole, Poland.
authors.forename: V V
authors.initials: VV
authors.lastname: Laguta
authors.forename: S
authors.initials: S
authors.lastname: Kamba
authors.forename: M
authors.initials: M
authors.lastname: Maryško
authors.forename: B
authors.initials: B
authors.lastname: Andrzejewski
authors.forename: M
authors.initials: M
authors.lastname: Kachlík
authors.forename: K
authors.initials: K
authors.lastname: Maca
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
authors.forename: D G
authors.initials: DG
authors.lastname: Schlom