New Materials for Quantum Magnetism: Spin Dimer Compounds

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Technical:This individual investigator award supports experimental studies in the field of quantum magnetism, and specifically investigation of the high-field ordered states of spin dimer compounds. These materials comprise strongly coupled pairs of spins (dimers) which by virtue of the crystal structure only weakly interact with each other. For antiferromagnetic intradimer exchange the ground state is a product of singlets, but strong magnetic fields can close the spin gap to excited triplet states which are delocalized as a consequence of interdimer coupling. These systems provide an elegant realization of a lattice gas of hardcore bosons, in which the external magnetic field plays the role of the chemical potential and the interdimer interactions determine both the kinetic and potential energy of the delocalized triplets. Depending on the balance of the interdimer couplings the triplets either crystallize or condense at low temperatures, leading to qualitatively different magnetically ordered states. Despite considerable theoretical interest in these magnetic states, there are relatively few candidate materials. The aim of this new research program is to develop novel spin dimer compounds, the study of which will deepen our understanding of the magnetically ordered states of this unusual class of materials. Experiments performed both in the PIs laboratory and at national facilities probe the magnetic properties via both thermodynamic and scattering measurements. Materials developed as part of this program will be available to the broader US condensed matter community via collaboration. Students involved in this work will graduate skilled in experimental studies of magnetism and the science and art of crystal growth. Non-technical:The search for and discovery of new materials plays a vital role in the field of condensed matter physics and in the development of advanced technologies. This award funds a program that is focused on the development of new materials with novel magnetic properties. The study of magnetism and magnetic materials dates back to antiquity, but many fundamental questions remain unanswered about the ways in which atomic magnetic moments arrange themselves (i.e. order) with respect to each other at low temperatures. The scientific goal of this program is to understand the magnetically ordered states of spin dimer compounds, a novel class of magnetic material which provides some unique perspectives on magnetism and magnetic structures. Despite considerable theoretical interest in this area, and some natural advantages of these systems for studying specific aspects of magnetically ordered structures, there are relatively few candidate materials. The emphasis of this award is on the synthesis and characterization of new examples of spin dimer compounds. Experiments performed both in the PIs laboratory and at national facilities probe the magnetic properties of these materials via both thermodynamic and scattering measurements. Materials developed as part of this program will be available to the broader US condensed matter community via collaboration. Students involved in this work will graduate skilled in experimental studies of magnetism and the science and art of crystal growth.