EAPSI: Synthesis of Novel Magnetic Honeycomb Compounds to Explore New Physics and Emergent Phenomena

Kelly Zachary A, Baltimore MD

Investigators

Abstract

In nature often the whole is greater than the sum of its parts. Whethera flock of birds or a school of fish, one cannot accurately predict the behavior of these large groups by examining a single bird or fish in isolation. Arising group behaviors are examples of emergent phenomena, where increasing system complexity gives rise to new properties. Atoms, the fundamental building blocks of matter, can also display emergent behavior when part of larger groups. In solid materials, these emergent behaviors can lead to electrical conductivity, magnetism, and superconductivity. Superconductivity, which allows the flow of electricity with no energy loss, has applications in electrical power generation and distribution, medical instrumentation, and new technology. However, one of the main issues with superconducting materials is they must be at extremely low temperatures in order to work, making them difficult and expensive to operate. Despite discovering superconductivity over a century ago, little is known about its underlying cause. By discovering the mechanism of superconductivity, new, cheaper, and more practical compounds can be designed to achieve superconductivity at room temperature. It has been theorized that materials with special atomic structures, such as magnetic honeycomb compounds, could hold the key to understanding superconductivity. To synthesize these novel honeycomb materials, the PI will work directly with Professor Hiroshi Kageyama at Kyoto University in Japan. He is a world leader in the cutting-edge chemical techniques needed to create these compounds. Emergent phenomena can be discovered and understood by studying the structure-property relationships in materials. One emergent state of extreme interest in physics, the quantum spin liquid (QSL) state, has strongly interacting magnetic spins, constrained by the lattice geometry, inhibiting the spins from ordering in an energetically preferred antiferromagnetic arrangement. As a result, the spins remain disordered even at absolute zero leading to this spin liquid state theorized to be critical for high temperature superconductivity. Theoretical models have predicted several potential QSL candidates; most notably the distorted honeycomb lattice. The goal of this project is to prepare a novel class of honeycomb material exhibiting strong spin orbit coupling satisfying the theoretically Kitaev model to produce a unique type of quantum spin liquid. While previous attempts have been made, no one has ever synthesized this type of material. Therefore, a new approach utilizing innovative chimie douce (low temperature chemistry) and high pressure methods will be developed to prepare novel honeycomb iridates which should exhibit quantum spin liquid behavior consistent with the Kitaev model. This material will advance the understanding of how magnetism and magnetic interactions can be engineered to produce emergent phenomena. I will perform this work in collaboration with Professor Kageyama at Kyoto University, who is an expert in low temperature chemistry and has the extensive facilities and equipment to enable the science. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Japan Society for the Promotion of Science.