Laser-based film deposition and characterization

该提案涉及应用激光脉冲来生产和测量新材料。 这种材料的生产是通过一种称为激光烧蚀沉积的过程进行的。 在这个过程中，强激光脉冲被用来从目标蒸发材料。 喷射材料的羽流被收集在基底上。 在正确的条件下，可以用这种方法生产结晶膜。 本提案中生产的材料主要是超导体、II-VI族半导体和磁性材料。 我们目前正在研究的超导体是YBCO，它是最有名的高温超导体。 我们感兴趣的是研究强光脉冲或大电流对这种材料超导性的部分破坏。 这项研究可能会为这些材料的耗散提供见解，为更高的电流铺平道路。 我们也有兴趣通过生长具有良好超导性能的厚膜来获得更高的电流。许多材料将使用来自超短激光脉冲的THz辐射进行研究。 太赫兹辐射跨越微波和红外辐射之间的光谱，是电子行为的有价值的探针。 我们正在开发一种新型的太赫兹光谱，特别是敏感的法拉第效应。（光场的偏振被磁场旋转。）除了磁性材料的研究外，这种光谱学可能被证明对生物医学应用有价值。 原因是许多生物分子的手性通过旋转透射光的偏振来模拟磁场。 由于水和其他非生物分子不具有这种性质，它们对观察到的信号没有贡献。

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.