Growth of cobalt manganese aluminum thin films by pulsed laser deposition.

Abstract

Half metallic ferromagnets (HMF) have a band gap for minority electrons at the Fermi level, so that only one spin state is occupied at T=0 K. These materials acquire remarkable properties for which the conduction is metallic only for one direction of electron spin and insulating for the other spin direction. Heusler alloys (such as Co₂MnAl, and Ni₂MnGa) constitute an important class of HMF among several other types such as iron oxide (Fe₃O₄), rutile (CrO₂); as well as dilute magnetic semiconductors (ZnMnSe, GaMnAs). Since their discovery, Heusler ferromagnets have received considerable attention due to better control of stochiometry and more diverse magnetic and structural phenomena. Furthermore, on the technological level, Heusler ferromagnets are suitable candidates for room temperature devices due to their high degree of spin polarization, their structure that matches most of zincblende semiconductors, and their high ferromagnetic transition temperature (Tc 600K). The synthesis and characterization of half-metal based compounds thin films represent an interesting and challenging task for spintronics devices. Pulsed laser deposition (pld) s a highly flexible and conceptually simple technique that offers the possibility of synthesizing novel materials under conditions that are far from thermal equilibrium. In this work, we are proposing to investigate the synthesis of Heusler ferromagnet alloys (Co₂MnAl) thin films by the PLD technique. Our goal is to investigate the structural properties of the Heusler materials grown by PLD. Later on studies should follow by tunneling and optical experiments to study the generation of photocurrent into the semiconductors. The stochiometry, crystalline phases, surface structure and physical properties of the gown layers will be systematically investigated as a function of deposition parameter, namely, laser intensity, deposition pressure and substrate temperature. This thesis project aims to control and optimize the growth condi