J.L. Loison

Epitaxial thin films of multiferroic GaFeO3 on conducting indium tin oxide (001) buffered yttrium-stabilized zirconia (001) by pulsed laser deposition

Epitaxial films of an alternative multiferroic material, GaFeO3 (GFO), were grown by pulsed laser deposition on yttrium-stabilized zirconia (001) and on conducting buffer layers of indium tin oxide (001). They present a perfect epitaxial growth along the GFO [010] axis and six crystallographic variants in the film’s plane. Their magnetic properties are close to those of the bulk with an out-of-plane [010] hard direction and a Curie temperature of ∼200K. The films did exhibit ferroelectric properties when characterized by electrostatic force microscopy.

Diversity of the magnetic coupling behaviors in the CoFe2∕CoFe2O4 system

The CoFe2∕CoFe2O4 system has been considered for use as hard electrodes in spin valve devices. In this letter, we focus on the nature and intensity of the magnetic exchange coupling between the two phases. CoFe2∕CoFe2O4 and CoFe2O4∕CoFe2 bilayers were fabricated by pulsed laser deposition from a metallic CoFe2 alloy target in a vacuum and in an O2:N2 oxidizing atmosphere for the metallic and oxide layers, respectively. Depending upon the elaboration conditions, three different coupling behaviors have been observed: Ferromagnetic, biquadratic, and antiferromagnetic. The minor loop shift and the apparent coercive field of the metal observed in the first two cases are of several hundreds of Oe for a metal thickness of 10nm. Those very large loop shifts and coercive fields confirm the potential usefulness of this system in terms of applications.

Epitaxial growth of one-dimensional Ca3Co2O6 thin films prepared by pulsed laser deposition

We report on the growth and structural properties of Ca3Co2O6 thin films deposited by pulsed laser ablation on SrTiO3 substrates heated at 700°C. In situ reflection high-energy electron diffraction and ex situ atomic force microscopy observations reveal that Ca3Co2O6 grows in a three-dimensional (3D) mode with a surface roughness of about 1.5nm rms. X-ray diffraction and cross-section transmission electron microscopy characterizations show that the deposited films are epitaxial without secondary phases and with a preferential growth orientation perpendicular to the (220) plane. Temperature dependent magnetization measurements reveal that the ferrimagnetic-ferromagnetic transition in the Ca3Co2O6 film is shifted toward higher temperatures with respect to the bulk cobaltite.

Structural and Optical Properties of Cd1—xZnxTe Epilayers Grown on GaAs (001) by Pulsed Laser Deposition

Epilayers of Cd 1-x Zn x Te on GaAs (001) substrates were grown by a pulsed laser deposition technique, using either polycrystalline or cold-pressed targets. The composition and structural quality of these epilayers were investigated by energy dispersive X-ray analysis, and X-ray diffraction. A large and widely tunable induced optical absorption has been observed in these CZT epilayers.

Tuning the coercive field of CoFe2 in hard/soft CoFe2O4/CoFe2 bilayers

The sensitivity of magnetoresistive devices, i.e. their ability to be switched by very small fields, depends on the softness of their soft electrode. In this paper, we show the possibility to tune the coercive field of the CoFe2 alloy, commonly used as a soft electrode, from intrinsic values down to zero, by varying the pulsed laser ablation conditions of CoFe2/CoFe2O4 bilayers. This tuning possibility relies on the existence of a frustration of the spins of the CoFe2 layer originating from both the ferrimagnetic nature of the CoFe2O4 layer and the oxide/metal interface roughness.

Optical nonlinear properties of Cd1−xZnxTe epilayers grown on (100) GaAs by pulsed laser deposition

Abstract This paper reports induced absorption in Cd 1− x Zn x Te thin films epitaxially grown by pulsed laser deposition on (100)-oriented GaAs substrate. The high optical nonlinearity is adjustable in the visible over a wide spectral region as the concentration x is varied.