Seifu Research Group
I-Nano-wires and nano-magnets
In recent years there has been a significant effort to develop new lower-dimensional solid state structures such as nano-wires and nano-magnets with optical, electronic, and magnetic characteristics governed by quantum mechanics. Understanding these structures is extremely important in order to probe size effects as well as to develop new technologies. The quest to develop new technologies is at the heart of materials physics research. The structure-property relations are determined by the conditions under which materials are grown. In this research several methods for filling carbon nano-tubes with magnetic nano-particles are explored and samples are characterized using magnetic and electron microscopy measurements.
II- Thin and ultra-thin nano-metric films
Thin films reveal unique properties with attractive effects for technological applications, such as giant magneto-resistance, tunneling magneto-resistance, as well as exchange couplings. Nanometric or ultrathin films exhibit an out-of-plane uniaxial surface anisotropy sufficient to overcome demagnetizing field which is an important feature for higher density magnetic media. Thin films in addition to their enormous potential for technological applications are attractive research objects to study surface and interface physics. On these quasi free standing structures the effects of reduced dimensionality can be studied because of the very weak interaction between film and the substrate. Films are characterized using in-house built magneto optic Kerr effect (MOKE), magneto meters, atomic and magnetic force microscopy.
Films are synthesized using state of the art DC / RF magnetron sputtering shown below. Sputtering Axxis tool purchased from Kurt J. Lesker Company (http://www.lesker.com) by Dr. Seifu at Morgan State University through a grant from the National Science Foundation Major Research Instrumentation. The Axxis tool is at present equipped with both DC and RF sputtering. At present the sputtering system has three DC source guns all running from the same power supply but one of the three has an RF power supply and tuner and can work in tandem and can be switched between RF and DC. With future funding resources the Axxis tool can be upgraded for atomic layer deposition and e-beam sputtering.
III- Mechanical Alloying
Mechanical Alloying is a novel method used to prepare nanostructured materials. This method creates true alloys of metals and metal oxides that are very difficult or impossible to combine by conventional means. In this method pure elemental powders are mixed in an intended proportion in a stainless steel container with stainless steel balls. The device is water or air cooled to keep the temperature close to room temperature in order for the synthesis to be purely mechanical. Mechanical alloying was first used to prepare dispersion-strengthened alloys. During the last few years it has been used to prepare a variety of applications-related magnetic materials and amorphous materials in the composition ranges that cannot be prepared by conventional means.
For inter-atomic mixing to occur the process of mechanical alloying first reduces grain sizes of crystalline material to few nanometers which brings about significant changes to properties of a material. A nanometer is 80,000 times smaller than the width of a human hair. When controlling matter at this scale, different laws of physics come into play. Properties of traditional materials change and behavior of surfaces start to dominate bulk. In recent years there has been a tremendous interest in nanostructured materials, foreseeing the potential this area of research will have on technology since the ultimate stage of miniaturization is nanoscale.