The project will experimentally investigate the unusual properties of geometrically frustrated magnets, materials in which the interactions between atomic spins compete with each other due to the particular geometry of the magnetic sublattice. The frustration in these materials leads to highly degenerate low temperature states in which the interaction energies cannot all be simultaneously minimized. The specific research goals of the project are to explore new geometrically frustrated magnetic materials, especially through the introduction of magnetic disorder; to examine the nature of unusual glass-like ground states in these material systems; and to explore the nature of residual 'ground state' entropy in these systems and others. The experiments will involve a range of thermodynamic experimental techniques and will be conducted in close collaboration with sample growers who can provide unique and important samples of new materials. Students involved in the research will participate in traditional and cutting edge training in a wide range of experimental techniques that will prepare them for careers in academe, industry or government.
This is a research program into the physics of a group of materials known as rare earth geometrically frustrated magnets. The magnetic atoms in these materials are unable to point their magnetic axes (known as the magnetic moments) in a unique way to minimize their energy. The root cause of this inability to minimize the energy is the geometrical arrangement of the magnetic atoms within the materials, and this geometrical arrangement makes these materials excellent models for a wide range of other complex systems which are similarly 'frustrated'. In particular, this research program will probe the effects of disorder in such systems and the nature of the unusual states of matter which are intrinsic to such frustrated systems. Understanding these magnetic materials has implications for other systems as diverse as superconducting junction arrays and glasses, and may also provide insight into computational algorithms. The principal investigator has an extensive record of working with a diverse group of students and involving graduate students and undergraduates in every stage of the research process. Students involved in the research will participate in traditional and cutting edge training in a wide range of experimental techniques that will prepare them for careers in academe, industry or government.
The research activities under this grant have focused on the investigation of a range of geometrically frustrated magnetic materials. These studies have been conducted through experimental measurements of thermodynamic and magnetic properties of the materials. Geometrically frustrated magnetic materials are important model systems for understanding the physics of complex systems that are composed of many interacting parts. By understanding these systems better, a range of technologies and materials with technological applications can be improved. The specific focus of the research in this grant was on materials that display "spin ice" and "spin liquid" behavior. These behaviors are exotic phenomena that occur only at temperatures close to absolute zero, but they have analogs in a range of materials such as ordinary water ice and glass, and their understanding has the potential to enable improved materials as well as the possibility of applications within magnetic memory devices. The activities have been primarily conducted by graduate students, the training of whom has been the major educational component of the program. Those two students have graduated and are working in industry and in STEM educational outreach activities, an in both cases their experience working in the laboratory setting has prepared them for their current career path. A supplement to this grant has also supported undergraduates working on experimental studies of the physics of granular materials and studies of frustrated magnetic nanostructures.
