TUNING COMPLEX MAGNETIC ORDER IN GARNETS AS A ROUTE TO SINGLE-PHASE ROOM TEMPERATURE MULTIFERROICS
Abstract
The work proposed is a detailed investigation into the structure and properties of transition metal and rare-earth garnets with the goal of developing materials with novel magnetic properties at room temperature that could revolutionize selected military technologies. Of particular interest is the development of materials that can incorporate multiple functional properties into single-phase materials like magnetoelectric multiferroics. Using their knowledge of solid state chemistry and materials science, the PI and his group will investigate new compositions of well-ordered, single phase garnets with stoichiometric concentrations of magnetic cations in each of the sites. Garnets are a particularly promising sandbox for understanding structure-property relationships due to the presence of three uniquely coordinated sublattices (tetrahedral, octahedral, and cubic) each of which can accommodate nearly every transition-metal or main group element in the periodic table. This kind of compositional diversity is rare in inorganic materials adopting the same structure and offers the potential to systematically tune the strength of the magnetic interactions through cationic substitution. As such, this work will endeavor to build the fundamental understanding of the magnetic interactions that occur between each of the unique sublattices. Following the discovery of large magnetostriction and magnetoelectric coupling in Tb3Fe5O12 and Dy3Fe5O12, this work will investigate new compositions derived from R3Fe5O12 and R3Cr2Fe3O12, where R can be any rare-earth or 3d transition metal, for the presence of multiferroic behavior near room temperature. The highly complex and diverse number of magnetic interactions in garnet is expected to result in the discovery of several compositions which adopt complex non-collinear magnetic structures like spiral, conical, or helical ordering and, by extension, demonstrate magnetoelectric multiferroic coupling. Magnetoelectrics, defined as materials which exhibit a coupling between their magnetism and the crystalline lattice, are extremely promising for applications in energy-efficient magnetic field sensors, high-density data storage, as well as next-generation RF power amplifiers. The early selection of materials will be guided using Density Functional Theory calculations to predict phase stability and the strength of magnetic interaction, after which compositions with the most potential will be optimized through systematic variations in the metal content to enhance the properties. The best materials will be characterized using X-ray and neutron scattering, temperatureand field-dependent magnetization measurements, as well as dielectric and impedance spectroscopies. If successful, this project will significantly advance our understanding of how to design materials that exhibit a strong coupling between their ferroelectric and magnetic properties at room temperature, which would have wide-reaching impact in the development of field-tunable electronic components. Understanding the way magnetism and ferroelectricity interact is of fundamental importance in developing faster, field programmable electronics and higher performance sensor technology. With a set of design rules in hand, compounds can be targeted and prepared at a substantially faster pace to meet the challenges of the ever-evolving needs of the modern warfighter.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 12, 2016
- Source ID
- N000141512411
Entities
People
- Brent C Melot
Organizations
- Office of Naval Research
- United States Navy
- University of Southern California