Interfacial Coupling and Magnetic Competition in Magnetic and Magnetoelectric Systems
In the American economic system, competition is a critical driver of performance and innovation. The same can be said for materials physics. My group focuses on studying a variety of strongly correlated quantum systems, where the competition between charge, spin and orbital degrees of freedom can lead to novel or enhanced properties. It is this sensitivity that makes these materials useful for devices. A good device has a measured property (such as resistance or magnetization) that changes dramatically with an external stimulus (such as current, temperature or magnetic field). Competition is a valuable strategy for creating this interplay of parameters. Magnetic competition in magnetic systems, on the other hand, has often been seen as a hindrance. While it typically decreases the overall net magnetization, I will show that it can be utilized to generate novel phenomena useful for devices, such as giant negative magnetization and enhanced magnetization at small applied fields. While much research on magnetism utilizes large fields to strengthen the net magnetization, most devices will need to utilize small fields. While my group also collaborates on a wide range of other systems (such as topological insulators, delafossites and transition edge sensors), much of our focus has been to grow high-quality films and understand the interfacial interactions in magnetic and magnetoelectric layers. I will discuss our first observation of a magnetoelectric dead layer, which motivated our recent interest and successes in magnetic phase competition and then some of the interesting features we have discovered in complex oxide thin films.