Showing papers by "Stéphane Fusil published in 2011"
TL;DR: Ab initio calculations of realistic interface structures provide insight into the origin of the induced moments and bring support to this new approach for creating room-temperature multiferroics.
Abstract: With only a few known useful room-temperature multiferroics, other ways of achieving materials showing magnetism as well as electrical polarization are sought. The discovery that the ferroelectric BaTiO3 also shows magnetism at room temperature at the interface with iron or cobalt marks a new approach to achieving multiferroic properties.
350 citations
TL;DR: It is shown that this form of magnetoelectric coupling, together with the possibility to reversibly design the ferroelectric domain structure, allows the electrostatic manipulation of magnetic flux quanta.
Abstract: Using heterostructures that combine a large-polarization ferroelectric (BiFeO3) and a high-temperature superconductor (YBa2Cu3O(7-δ)), we demonstrate the modulation of the superconducting condensate at the nanoscale via ferroelectric field effects. Through this mechanism, a nanoscale pattern of normal regions that mimics the ferroelectric domain structure can be created in the superconductor. This yields an energy landscape for magnetic flux quanta and, in turn, couples the local ferroelectric polarization to the local magnetic induction. We show that this form of magnetoelectric coupling, together with the possibility to reversibly design the ferroelectric domain structure, allows the electrostatic manipulation of magnetic flux quanta.
108 citations
TL;DR: This work reveals the coexistence of two differently distorted polymorphs that leads to striking features in the temperature dependence of the structural and multiferroic properties, which hold promises of giant piezoelectric, magnetoelectrics, and piezomagnetic responses.
Abstract: In multiferroic ${\mathrm{BiFeO}}_{3}$ thin films grown on highly mismatched ${\mathrm{LaAlO}}_{3}$ substrates, we reveal the coexistence of two differently distorted polymorphs that leads to striking features in the temperature dependence of the structural and multiferroic properties. Notably, the highly distorted phase quasiconcomitantly presents an abrupt structural change, transforms from a standard to a nonconventional ferroelectric, and transitions from antiferromagnetic to paramagnetic at $360\ifmmode\pm\else\textpm\fi{}20\text{ }\text{ }\mathrm{K}$. These coupled ferroic transitions just above room temperature hold promises of giant piezoelectric, magnetoelectric, and piezomagnetic responses, with potential in many applications fields.
93 citations
TL;DR: In this paper, a bottom-up approach for the fabrication of spin-transfer nano-oscillators (STNOs) is presented, where porous alumina is used as a template for the growth by electrodeposition of metallic spin valves in series.
Abstract: We report on a bottom-up approach for the fabrication of spin-transfer nano-oscillators (STNOs). Porous alumina is used as a template for the growth by electrodeposition of metallic spin valves in series. Under specific magnetic field and injected current conditions, emission of microwave current is detected with frequency in the 1.5 GHz range and linewidth as low as 8 MHz. We find strong indications that the microwave emission is due to spin-transfer-driven vortex oscillations. This technique is promising for the fabrication of dense arrays of STNOs in view of device synchronization.
14 citations
TL;DR: In this paper, the magnetotransport characteristics of nanospintronics single-electron devices are investigated, and the authors attribute the observed magnetoresistance to either spin accumulation or anisotropic magneto-Coulomb effect, two effects with very different origins.
Abstract: We investigate the magnetotransport characteristics of nanospintronics single-electron devices. The devices consist of single nonmagnetic nano-objects (nanometer-size nanoparticles of Al or Cu) connected to Co ferromagnetic leads. The comparison with simulations allows us attribute the observed magnetoresistance to either spin accumulation or anisotropic magneto-Coulomb effect (AMC), two effects with very different origins. The fact that the two effects are observed in similar samples demonstrates that a careful analysis of Coulomb blockade and magnetoresistance behaviors is necessary in order to discriminate them in magnetic single-electron devices. As a tool for further studies, we propose a simple way to determine if spin transport or the AMC effect dominates from the Coulomb blockade $I$-$V$ curves of the spintronics device.
4 citations
TL;DR: In this article, the authors present the design and fabrication of thin film electro-optic modulators based on thin film heterostructures using BiFeO3 as the active modulating medium.
Abstract: The ferroelectric bismuth ferrite (BiFeO3) exhibits a strong spontaneous polarization and potentially large electro-optic coefficients. We present our efforts in the design and fabrication of thin film electro-optic modulators based on thin film heterostructures using BiFeO3 as the active modulating medium.