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Energy harvesting from sunlight is essential in order to save fossil fuels, which are found in limited amount in the earth's crust. Photovoltaic devices converting light into electrical energy are presently made of semiconducting materials, but ferroelectrics are also natural candidates because of their internal built‐in electric field. Although they are clearly uncompetitive for mainstream applications, the possibility to output high photovoltages is making these materials reconsidered for targeted applications. However, their intrinsic properties regarding electronic transport and the origin of their internal field are poorly known. Here, it is demonstrated that under intense illumination and electric field, oxygen vacancies can be controllably generated in BiFeO3to dramatically increase the conductance of BiFeO3single crystals to a controllable value spanning 6 orders of magnitude while at the same time triggering light sensitivity in the form of photoconductivity, diode, and photovoltaic effects. Properties of the bulk and the Schottky interfaces with gold contacts are disentangled and it is shown that bulk effects are time dependent. The photocurrent has a direction that can be set by an applied field without changing the ferroelectric polarization direction. The self‐doping procedure is found to be essential in both the generation of electron hole pairs and the establishment of the internal field that separates them.

We show that Sm10Co90amorphous films exhibit anisotropic magnetostriction effects when a magnetic field is applied perpendicular to the imprinted easy axis of magnetization. At low applied fields (0-100 mT), we observe strong anisotropy in the field response. Parallel to the applied field, the strain scales linearly with the applied field while the strain perpendicular to the field direction (easy axis) is close to the detection limit. This behavior is accompanied by zigzag domain wall motion with the corners pointing along the easy axis. The origin of the anisotropic magnetostriction is discussed.

We report on the effect of carbon implantation on the structural, electronic, and magnetic properties of Fe93Zr7(FeZr) amorphous films. Extended X-ray absorption fine structure measurements on (FeZr)100-xCx(x= 0, 5.5, and 11) indicate the incorporation of carbon in the FeZr matrix, with an increase of the Fe-Fe distance by implanting carbon. X-ray photoelectron spectroscopy measurements reveal the creation of Fe-C bonds after implantation. A significant enhancement of the Curie temperature and decrease of the coercivity are observed in the carbon-implanted films. Moreover, the non collinear ferromagnetism of the as-grown FeZr film diminishes upon carbon implantation.

We show that Sm10Co90 amorphous films exhibit anisotropic magnetostriction effects when a magnetic field is applied perpendicular to the imprinted easy axis of magnetization. At low applied fields (0-100 mT), we observe strong anisotropy in the field response. Parallel to the applied field, the strain scales linearly with the applied field while the strain perpendicular to the field direction (easy axis) is close to the detection limit. This behavior is accompanied by zigzag domain wall motion with the corners pointing along the easy axis. The origin of the anisotropic magnetostriction is discussed.

We report on the effect of carbon implantation on the structural, electronic, and magnetic properties of Fe93Zr7 (FeZr) amorphous films. Extended X-ray absorption fine structure measurements on (FeZr)100-xCx (x = 0, 5.5, and 11) indicate the incorporation of carbon in the FeZr matrix, with an increase of the Fe-Fe distance by implanting carbon. X-ray photoelectron spectroscopy measurements reveal the creation of Fe-C bonds after implantation. A significant enhancement of the Curie temperature and decrease of the coercivity are observed in the carbon-implanted films. Moreover, the non collinear ferromagnetism of the as-grown FeZr film diminishes upon carbon implantation.

Optical measurements have been carried out on high-quality BiFeO3single crystals in order to show the presence of electronic defect states and calculate the band gap. The photoluminescence spectra show an intense electronic transition peak at a wavelength of 410 nm. This peak is large and asymmetric, indicating the existence of defects inside the gap, which we attribute to oxygen vacancies. These defects are likely to originate from the slow heating rate and long sintering times necessary to synthesize BiFeO3single crystals. The optical band gap is measured to be 3 eV, a larger value than those previously reported.

Optical measurements have been carried out on high-quality BiFeO3 single crystals in order to show the presence of electronic defect states and calculate the band gap. The photoluminescence spectra show an intense electronic transition peak at a wavelength of 410 nm. This peak is large and asymmetric, indicating the existence of defects inside the gap, which we attribute to oxygen vacancies. These defects are likely to originate from the slow heating rate and long sintering times necessary to synthesize BiFeO3 single crystals. The optical band gap is measured to be 3 eV, a larger value than those previously reported.