Peter is off to Los Alamos National Laboratory for several months where he will be working with Aiping Chen at the Center for Integrated Nanotechnologies (CINT) on growth kinetics of entropy stabilized oxides.

Peter was chosen to receive the Graduate Excellence in Materials Science (GEMS) award from the American Ceramic Society (ACerS). Congratulations!

Peter gives a talk on the magnetism of entropy-stabilized oxides at MS&T 2018 in Columbus, OH, entitled Structurally Driven Magnetic Disorder in Entropy-Stabilized Oxides.

Abstract: A unique benefit to entropic stabilization is the increased solubility of elements, which opens a broad compositional space with subsequent local chemical and structural disorder resulting from different atomic sizes and preferred coordinations of the constituents. In the antiferromagnetic entropy-stabilized oxides studied here, we see that by tuning the chemistry, and thus the concentration of local structural distortions, we can either induce or reclaim a large degree of frustration in the magnetic lattice of the material. This effect can then be engineered to enhance the strength of the magnetic exchange field by a factor of 10x in ferromagnetic/antiferromagnetic heterostructures, when compared to a “normal” antiferromagnetic oxide, such as CoO. Our results reveal that the unique characteristics of entropy stabilized materials can be utilized to engineer and enhance magnetic functional phenomena in oxide thin films, as well as offer a powerful platform for the study of defects and functional properties.

Congratulations to Sieun for passing her candidacy exam on September 4th.

Doping is an essential step in semiconductor technology to achieve the desired type and level of electrical conductivity. Thus, predicting both n-type or p-type dopability of a material is a prerequisite to exploit the material for electronic application. First-principles calculations are a powerful tool to understand point-defect properties since experimental studies to identify and characterize defects at the atomic scale are challenging. To predict n-type and p-type dopability of an unexplored wide bandgap material, we investigated the thermal stability and charge state of various intentional dopants, the issues regarding carrier localization, and charge compensation from native defects.

“The ability to use an electric or magnetic field to manipulate the orientation of electric dipoles or magnetic moments associated with atoms, ions or molecules in a material provides a vast array of functions. In rare materials called magnetoelectric multiferroics, the dipoles are intimately coupled to the moments, and a single field can control both¹. After the field is applied, however, the dipoles and moments typically all have the same orientation, and the original pattern that they formed is lost. In a paper Nature, Leo et al.² show that, in two particular materials, a magnetic field can flip each of the dipoles or moments while preserving the structure of the original pattern. The work illustrates how the complex coupling in these materials could be used to uncover other, previously unobserved electric and magnetic effects.”

Full text available from Nature