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We have deposited magnetite thin films using the pulsed laser deposition technique from a α-Fe2O3 target on different substrates (Si (1 1 1), GaAs (1 0 0), Al2O3 (0 0 1) and amorphous float glass (FG)) without any buffer layer at a substrate temperature of 450 °C. These films have been characterized by x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, ac magnetic susceptibility and four-probe resistivity. The XRD results of these films show highly (1 1 1) oriented growth and single phase nature of Fe3O4 films on all substrates. Fe 2p core level x-ray photoelectron spectra and Raman spectra reveal the formation of Fe3O4 throughout the thickness of the films. All films show a Verwey transition at or around 120 K. It is observed that the oriented growth of Fe3O4 films takes place along the [1 1 1] direction on these substrates, which have either a huge lattice mismatch or no matching at all (as in FG) with Fe3O4.

In this work a Mn doped magnetoelectric BiFeO 3 system is studied. Xray diffraction (XRD), scanning electron microscopy, energy dispersive xray analysis (EDX), Mössbauer spectroscopy at room and high temperatures, differential scanning calorimetry (DSC), high temperature magnetization, dielectric constant measurements and x-ray photoelectron spectroscopy (XPS) are used to characterize the samples. The XRD result shows BiFeO 3 as a major phase along with about 1-2% impurity phase. EDX shows the equi-atomic ratio of Bi and Fe site cations. Using DSC it is observed that the Néel temperature decreases with Mn doping. Using Mössbauer and XPS it is observed that Fe exists in the +3 oxidation state. The samples have an antiferromagnetic nature with Mn doping.

We present a Raman study of Fe3O4 (100) thin films across the Verwey transition in the temperature range of 85–300K. These films are epitaxially grown on MgO (100) substrate by pulsed laser deposition technique. X-ray diffraction and low temperature resistivity measurements reveal that these films exhibit high structural order and perfect stoichiometry with Verwey transition at 121K. The frequency of different Raman modes [A1g and T2g(2)] changes abruptly around the Verwey transition temperature (TV). Below TV we observe a splitting in T2g(3) mode. Using Allen’s formula [Solid State Commun. 14, 937 (1974)] the strength of the electron-phonon coupling (λ) is estimated from the observed line shape parameters, and our estimates show that in epitaxially grown Fe3O4 thin films strong electron-phonon coupling is present. This coupling parameter is larger for T2g(3) mode as compared with that of A1g and T2g(2) modes. It is also observed that the coupling parameter corresponding to A1g mode remains invariant going from bulk single crystal to thin film while that of T2g(2) and T2g(3) modes are almost doubled. An attempt has been made to correlate the observed behavior with the presence of antiphase boundary in epitaxial thin films.

We present Raman study of Fe3O4 films of different thicknesses grown on single crystal Si and MgO substrates to investigate the presence of antiphase boundaries (APBs). X-ray diffraction and x-ray photoelectron spectroscopy measurements indicate that films are single phase Fe3O4 on both the substrates. The changes in frequency and linewidth of different Raman modes [A1g and T2g(3)] are monitored and the electron-phonon coupling parameter (λ) is computed. λ is correlated with the combined effect of strain and APBs present in the grown films and it is concluded that the films grown on Si substrates are free from APBs.