The overall goal of this RUI project is to better understand the fundamentals of ferromagnetism in carrier mediated n-type transition metal (TM)-doped In2O3 dilute magnetic semiconductors (DMS). Ferromagnetic behavior after doping, high Curie temperature, and controllable carrier density are some of the crucial requirements for developing spin-based multifunctional devices. TM-doped In2O3 is such a unique system, for which control of the defect concentration can tune the electrical/magnetic behavior from ferromagnetic metal-like to ferromagnetic semiconducting to paramagnetic insulating. The charge carrier density of thin films of DMS, grown by pulsed laser deposition, will be controlled through doping, growth parameters during deposition, and post-deposition annealing. Structural and interfacial details at atomic scale will be examined by various state-of-the-art techniques such as X-ray diffraction, Raman spectroscopy, atomic force microscopy, field emission scanning electron microscopy, and transmission electron microcopy. Ferromagnetism and its correlations with electronic properties will be investigated through magnetization and magneto-transport studies at high and low magnetic fields and at temperatures down to 2 K using a superconducting quantum interference device magnetometer and a high field magneto-transport set-up. Experimental data will test current theoretical models proposed for DMS. An understanding of spin physics arising from this research will lead to the potential development of new spintronic devices such as ultra-sensitive magnetic field sensors, quantum-based logic, and memory for high speed computation. This research project will motivate and encourage undergraduate students realize a firmer understanding of magnetism, semiconductor physics, and spin-electronic devices.
Ferromagnetism arises due to the ordering of the magnetic moments of neighboring electrons such that they point in the same direction. A number of materials show ferromagnetism at low temperatures, but only iron, cobalt, nickel, and some alloys show ferromagnetism above room temperature for useful applications. Dilute Magnetic Semiconductors (DMS) belong to a new class of ferromagnets, which are formed by incorporating dilute amount of transition metals such as iron or cobalt into normal semiconductors such as GaAs, ZnO, or In2O3. Ferromagnetic behavior after doping, high Curie temperature, and controllable electron density are the crucial requirements for developing spin-based multifunctional devices. The overall goal of this RUI project is to better understand the fundamentals of ferromagnetism and control magnetism in electron carrier mediated transition metal (TM)-doped In2O3 dilute magnetic semiconductors (DMS). The electron carrier concentration of thin films of DMS, to be grown by pulsed laser deposition, will be controlled through chemical doping, growth parameters during deposition, and post-deposition annealing. Structural, magnetic, and electronic properties will be investigated by various state-of-the-art techniques such as X-ray diffraction, optical spectroscopy, atomic force microscopy, electron microcopies, and superconducting quantum interference device magnetometry. Experimental results will be analyzed using the theoretical models which have been proposed for DMS. This research will lead to a deeper understanding of the phenomenon of ferromagnetism in DMS which will lead to the potential development of new spin-based devices such as ultra-sensitive magnetic field sensors, quantum-based logic, and memory for high speed computation. Training and skills acquired by undergraduate and graduate MS students through this research will serve them well for employment in high-tech industry, academic institutions, and government and private research laboratories.
