Laser-based film deposition and characterization

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This proposal involves the application of laser pulses to produce and measure novel materials.  The production of the materials is through a process called laser ablative deposition.  In this process, an intense laser pulse is used to vapourize material from a target.  The plume of ejected material is collected on a substrate.  Under the correct conditions a crystalline film can be produced in this way.  The materials to be produced in this proposal are primarily superconductors, II-VI semiconductors and magnetic materials.   The superconductor we are currently studying is YBCO, the best known of the high temperature superconductors.  We are interested in studying the partial destruction of the superconductivity in this material by intense optical pulses or large currents.  This research may provide insights into dissipation in these materials paving the way for higher currents to be carried.  We are also interested in achieving higher currents by growing very thick films with good superconducting properties. Many of the materials will be studied using THz radiation derived from an ultrashort laser pulse.  THz radiation spans the spectrum between microwaves and infrared radiation and is a valuable probe of electronic behaviour.  We are developing a novel form of THz spectroscopy that is especially sensitive to the Faraday effect. (Rotation of the polarization of an optical field by a magnetic field.) This spectroscopy may prove to be of value for biomedical applications in additon to the study of magnetic materials.  The reason is that the chirality of many biomolecules mimics a magnetic field by rotating the polarization of transmitted light.  Since water and other non-biological molecules do not have this property they do not contribute to the signal observed.