Magnetism of Quantum Spins Systems in Low Dimensions

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This research involves the study of the magnetic properties of transition metal complexes in which the metal spins confined to one or two spatial dimensions (1D, 2D). Because of the low-dimensional couplings, the materials exhibit interesting magnetic phase diagrams as a function of temperature, magnetic field, and pressure. The phase behavior will be investigated by a range of experimental techniques, which include susceptibility and specific heat measurements that extend to temperatures as low as 50 millikelvin and field strengths up to 9 Tesla. These thermodynamic studies complement optical and magnetic resonance spectroscopy investigations. In one linear-chain material with S=2, the temperature dependence of the first critical magnetic field will be mapped and compared with theory and simulation studies, which predict possible new critical behavior. In two dimensions, novel layered materials based upon Prussian blue analogues will be investigated. These new systems are magneto-optically switched below 150 K. Students participating in the project will learn a wide range of modern experimental techniques, many of which require skills associated with attaining ultra low temperatures and very high magnetic fields. This training provides excellent preparation for careers in industry, academe and government. The primary impact of the research is on fundamental physics, though the research dealing with layered magnetic materials may have some technological relevance to the information storage industry.This project focuses on the investigation of novel magnetic systems confined to one or two spatial dimensions. A striking aspect of low dimensional systems is that their properties are often qualitatively and quantitatively predictable since new analytical and numerical tools are now available due to increased access to fast computers. The experimental research requires investigations at the extremes of low temperatures and high magnetic fields. The work presents stringent tests of the models and yields insight relevant to the information storage industry. The participating students receive training in a variety of interdisciplinary fields, namely physics, chemistry, and materials science, and are well prepared to enter the technologically diverse work force.