Effects of interdot dipole coupling in mesoscopic epitaxial Fe(100) dot arrays

The domain structure and the coercivity of epitaxial Fe(100) circular dot arrays of different diameters and separations have been studied using magnetic force microscopy (MFM) and focused magneto-optical Kerr effect (MOKE). The MFM images of the 1 µm diameter single domain dot arrays show direct evidence of strong interdot dipole coupling when the separation is reduced down to 0.1 µm. The coercivity of the dots is also found to be dependent on the separation, indicating the effect of the interdot dipole coupling on the magnetization reversal process

Quantized spin wave modes in micron size magnetic discs

We report on the observation of spin wave quantization in tangentially magnetized Ni80Fe20 discs by means of Brillouin light scattering spectroscopy. For a large wave vector interval several discrete, dispersionless modes with a frequency splitting up to 2.5 GHz were observed. The modes are identified as being magne-tostatic surface spin wave modes quantized by their lateral confinement in the disc. For the lowest modes dynamic magnetic dipolar coupling between the discs is found for a disc spacing of 0.1microm

Quantized spin wave modes in micron size magnetic discs

We report on the observation of spin wave quantization in tangentially magnetized Ni80Fe20 discs by means of Brillouin light scattering spectroscopy. For a large wave vector interval several discrete, dispersionless modes with a frequency splitting up to 2.5 GHz were observed. The modes are identified as being magne-tostatic surface spin wave modes quantized by their lateral confinement in the disc. For the lowest modes dynamic magnetic dipolar coupling between the discs is found for a disc spacing of 0.1microm

Technology for single mode TEM00 large diameter electrically pumped external-cavity VCSEL devices on electroplated gold substrate

International audienc

Technology for single mode TEM00 large diameter electrically pumped external-cavity VCSEL devices on electroplated gold substrate

International audienc

Nanoimprint and micro-contact printing tri-layer processes

Replication of patterns at a nanometer scale is a challenge for both advanced optical lithography and post-optical techniques. Considerable industrial effort has been devoted to the so-called leading-edge optical methods and the next generation lithography techniques. In parallel, a number of low-cost techniques such as nanoimprint and micro-contact printing are being investigated. In these methods, pattern replication is performed in non-conventional ways so that diffraction and scattering problems are no longer relevant. However, several other critical issues have to be studied. This paper describes two tri-layer pattern-transfer techniques, which can be used to improve the process latitude and the process compatibility. Pattern replication and lift-off transfer with feature sizes down to 30 nm and 150 nm have been achieved respectively by nanoimprint and micro-contact printing. As application examples, high-density magnetic dot structures are obtained and studied by measuring magneto-optical Kerr hysteresis loops

Single mode TEM00 large diameter electrically pumped external-cavity VCSEL devices on electroplated gold substrate

International audienc

X-ray photoelectron spectroscopy analysis of the effect of temperature upon surface composition of InP etched in Cl-2-based inductively coupled plasma

International audienceThe chemical composition of the surface of InP samples etched in Cl-2 and Cl-2/Ar inductively coupled plasma (ICP) is analyzed using ex-situ x-ray photoelectron spectroscopy (XPS). Comparison between ex-situ and in-situ XPS measurements shows that the stoichiometry of the etched surface can be retrieved from the ex-situ analysis provided that an adapted procedure is used. This allows for investigating the evolution of the surface stoichiometry as a function of etching parameters. The sample temperature is found to play a determining role in the top surface composition during etching. An abrupt switch from a rough and In-rich surface to a smooth and significantly P-rich surface is observed above a critical temperature and is found to depend only weakly upon the other etching parameters such as direct current bias or pressure. Ex-situ XPS measurements are used to estimate the thickness of the phosphorus layer identified on the top surface as similar to 1 nm, which is consistent with the value previously derived using in-situ XPS. Finally, the stoichiometry of the InP etched sidewalls is analyzed selectively using dedicated microscale periodic patterns. The surface P-enrichment of the etched sidewalls is found to be very similar to that of the bottom etched surface. The presence of the phosphorus top layer may have an impact on the sidewall passivation mechanism during anisotropic ICP etching of InP-based heterostructures using Cl-2-containing plasma chemistry