We report the structural and physical properties of epitaxial Bi 2 FeCrO 6 thin films on epitaxial SrRuO 3 grown on (100)-oriented SrTiO 3 substrates by pulsed laser ablation.The 300 nm thick films exhibit both ferroelectricity and magnetism at room temperature with a maximum dielectric polarization of 2.8 µC/cm 2 at E max = 82 kV/cm and a saturated magnetization of 20 emu/cc (corresponding to ~ 0.26 µ B per rhombohedral unit cell), with coercive fields below 100 Oe. Our results confirm the predictions made using ab-initio calculations about the existence of multiferroic properties in Bi 2 FeCrO 6 .

The influence of the deposition pressure PO 2 and substrate temperature T S during the growth of Bi 2 FeCrO 6 thin films grown by pulsed laser deposition has been investigated. It is found that the high volatility of Bi makes the deposition very difficult and that the growth of pure Bi2FeCrO6 thin films on SrTiO 3 substrates is possible only in a narrow deposition parameter window. We find that the pure Bi 2 FeCrO 6 phase is formed within a narrow window around an oxygen pressure PO 2 =1.2×10 −2 mbar and around a substrate temperature T S =680 °C. At lower temperature or higher pressure, Bi 7.38 Cr 0.62 O 12+x _also called (b*Bi 2 O 3 )and Bi 2 Fe4O 9 /Bi 2 (Fe,Cr) 4 O 9+x phases are detected, while at lower pressure or higher temperature a (Fe,Cr) 3 O 4 phase forms. Some of these secondary phases are not well known and have not been previously studied. We previously reported Fe/Cr cation ordering as the probable origin of the tenfold improvement in magnetization at saturation of our Bi 2 FeCrO 6 film, compared to BiFeO 3 . Here, we address the effect of the degree of cationic ordering on the magnetic properties of the Bi 2 FeCrO 6 single phase. Polarization measurements at room temperature reveal that our Bi2FeCrO6 films have excellent ferroelectric properties with ferroelectric hysteresis loops exhibiting a remanent polarization as high as 55-60 µC/cm 2 along the pseudocubic (001) direction.

An effective field model based on intrawire and interwire dipolar interactions has been developed in order to describe the magnetic anisotropy in arrays of homogeneous and multilayer nanowires. Variable angle ferromagnetic resonance (FMR) and vibrating sample magnetometry (VSM) characterization techniques were used to determine the effective interaction field acting on Ni, CoFeB, and Ni/Cu nanowires. FMR spectra are well described by a rigid magnetization model and VSM data are in rough agreement with a mean longitudinal field model. FMR and VSM values of the effective fields are mutually consistent and in fair agreement with the values calculated with the model. The results show that the anisotropy of our arrays is strongly dominated by the dipolar interactions.

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