Phase competition in thin magnetic oxide films: is the dead layer truly “dead”?

Tuesday, October 8, 2019 10:00 am - 10:00 am EDT

Robbyn Trappen, West Virginia University

The family of materials known as complex magnetic oxides have gained a great deal of attention as potential candidates in a number of novel energy saving device applications; however a major barrier to using these materials for their proposed applications has been due to the loss or reduction of magnetism in very thin or small magnetic materials, (typically at surfaces and interfaces) also called the magnetic dead layer problem, which despite extensive research continues to be a challenging issue to resolve.

One question that remains to be fully answered is what exactly is going on inside the dead layer? In this talk I will discuss some of the work that has been done in order to understand the factors that influence the suppression of magnetization as well as some recent insight that has been gained into the physics of these systems, namely the appearance of multiple competing types of magnetic order enhanced by a delicate interplay between the many material parameters. I will highlight some of our recent studies from WVU on the widely studied La0.7Sr0.3MnO3 and related compounds that have shed some light on the nature of this competition, as well as revealed unusual effects such as giant negative magnetization and exchange-spring like spin rotations across the films when measured with small magnetic fields. The extreme sensitivity of these systems to material parameters and defects poses a challenge that will need to be overcome for these materials to be fully utilized for their applications.