High-Resolution Leed Study of Intermixing of Fe Films on Au(001) Surface
- PDF / 419,265 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 31 Downloads / 171 Views
HIGH-RESOLUTION LEED STUDY OF INTERMIXING OF Fe FILMS ON Au(001) SURFACE Y.-L. He and G.-C. Wang Department of Physics, Rensselaer Polytechnic Institute, Troy, NY 12180-3590, USA
ABSTRACT Ultrathin ferromagnetic Fe films have been grown on an Au(001) surface. Using the angular profile measurements of High-Resolution LEED (HRLEED), we show the inhomogeneities at the interface due to atomic place exchange between Fe and Au atoms can drastically change the angular intensity distributions of diffraction beams. The contributions from the inhomogeneities on the surface can be properly decoupled from the total angular intensity distributions. Through the energy dependent angular profile analysis of diffraction beams, we have quantitatively determined the degree of inhomogeneous atomic intermixing at elevated annealing temperatures. I. INTRODUCTION The study of ultrathin magnetic films has been a challenging subject both technologically and scientifically. The low symmetry of the films can lead to desired magnetic anisotropies in directions differing from those of the bulk materials. It has been possible to prepare metastable two-dimensional (2D) ferromagnetic ultrathin films on non-magnetic substrates. Among those, Fe/Au systems have been studied extensively. It has been a common knowledge that the magnetic properties are essentially correlated to the structural properties of the films. However, there still remains a very important issue which needs to be addressed: how does the structural property change as a function of temperature? The most commonly used method to examine the thermal stability of the films is Auger electron spectroscopy (AES). A reduced Auger signal of a film material indicates a serious diffusion or intermixing. However, the structural property varies far beyond the detectability of AES. HRLEED has been used mostly to study the structural properties of homogeneous surfaces or non-intermixed heteroepitaxial interfaces. Recently, by using HRLEED work on atomic intermixing of NiSi 2 and SiO 2 on Si(111) has been reported.[1] In the present work we demonstrate that HRLEED can also be used to study the intermixing of a metal-on-metal system. II. EXPERIMENTAL The experiment was performed in a UHV chamber (--1X10- Torr) which is equipped with HRLEED optics, an Auger cylindrical mirror analyzer and an ion sputtering gun. The resolution of the HRLEED is -,6X10- 3A-1.[21 A Fe source was constructed with a piece of Fe foil. The foil was mounted in a sample housing and with a pancake-shaped W filament behind. For a precise measure of Fe dose a shutter was used between the source and substrate. The Au(001) surface has been extensively characterized and reported previously.[3] An average terrace width of -500A has been obtained in "flat" surface areas. All the LEED data reported here were collected in these areas. The Fe films were deposited at a rate of about 1ML/80sec and at a substrate temperature of 330K (due to thermal radiation from Fe source). The film growth was closely monitored with the HRLEED. At the ab
Data Loading...
