Electronic, magnetic, and superconducting properties of compounds and thin films

本文的目的是研究陶瓷氧化物和金属插层化合物的体和薄膜的电子、磁性和超导性。我的主要研究重点将是过渡金属氧化物（钙钛矿结构），它已经显示出丰富和非凡的物理性质，在技术上很重要，如高TC超导体和锰矿。在某些钙钛矿中，电子的轨道自由度以及它们的自旋和轨道之间的强耦合影响了它们的磁性和导电性。例如，钙钛矿，LaVO3在低温下经历了结构和反铁磁相变，新相中轨道和自旋顺序不同。另一种有趣的化合物是procoo3（可能用于电化学设备），它是一种没有磁跃迁的绝缘体。然而，用Sr或Ca代替（掺杂）La会导致这种材料在小磁场下表现出大的磁阻（MR）。我建议对应变和外部压力如何影响LaVO3的体和薄膜以及Pr(1-x)SrxCoO3的电子和磁性能进行以下研究。这将使我们能够调查并看看我们是否可以将这些材料的薄膜用于可能的应用。我的第二个目标是通过在石墨的碳层之间放置金属来研究超导性（插层石墨MC6， M=金属）。石墨是一种层状化合物，其中碳原子在平面内紧密结合，而在平面外弱结合。人们可以在这些平面之间放置不同的金属，这被称为插层。通过这样做，我们可以改变石墨的电子特性，例如，通过插入Ca（钙），它在低温下成为超导体。我们计划做的是在石墨中插入各种各样的原子，观察它的电子和磁性是如何变化的。这将帮助我们理解为什么插层石墨会成为超导体。

The objective of this proposal is to study electronic, magnetic and superconductivity of bulk and thin films of ceramic oxides and metal intercalated compounds. The main focus of my research will be on transition metal oxides (perovskite structure) which have shown rich and extraordinary physical properties that are technologically important, such as high TC superconductors and manganites. In some perovskite, the orbital degrees of freedom of electrons in conjunction with the strong coupling between their spin and orbit affect their magnetic and conducting properties. For example, perovskite, LaVO3 undergoes a structural and anti-ferromagnetic phase transition at low temperature with different orbital and spin ordering in the new phase. Another interesting compound is PrCoO3 (possible uses in electrochemica devices) which is an insulator with no magnetic transition. However, slight replacement (doping) of La with Sr or Ca causes this material to show large magneto-resististance (MR) with a small magnetic field. I am proposing to do the following research on how strain as well as external pressures affect the electronic and magnetic properties of the bulk and films of LaVO3 as well as Pr(1-x)SrxCoO3. This will allow us to investigate and to see whether or not we can use the thin films of these materials for possible application.My secondary objective is to study superconductivity by putting metals in-between carbon layers in graphite (intercalated graphite MC6, M=metal). Graphite is a layered compound where carbon atoms are strongly bounded in planes and weakly bounded out of plane. One can put different metals between these planes which is called intercalation. By doing this, we can change the electronic properties of graphite, for example, by intercalating Ca (calcium) it becomes, superconductor at low temperature. What we are planning to do is intercalate a variety of atoms in graphite and observe how its electronic and magnetic properties change. This will help us understand why intercalated graphite becomes a superconductor.