Frances Hellman

Research

My research group is concerned with understanding the physics of novel magnetic, semiconducting, and superconducting materials especially in thin film form. We apply a variety of techniques such as specific heat, magnetic susceptibility, electrical resistivity, and others as a function of temperature and field in order to test and develop models for systems with strong coulomb correlations where the Landau liquid model breaks down, challenging our understanding of metallic behavior, and to uncover novel magnetic phenomena. Thin film growth techniques are used to prepare materials not available by bulk preparation techniques, such as amorphous alloys, multilayers, or metastable materials. Current research includes: effects of spin on transport and tunneling, including studies of amorphous magnetically-doped semiconductors; novel magnetic materials and phenomena induced by strong spin orbit coupling and interfaces in heterostructures; finite size effects on magnetic and thermodynamic properties; tunneling level states, and energy landscapes in amorphous materials; formation of perpendicular magnetic anisotropy in magnetic thin films; and effects of the vapor-deposition growth process on the short and long range chemical and structural order in amorphous and crystalline alloys. We also have an extensive effort in development of calorimetry for thin films and small bulk samples. We use Si-microfabrication techniques to create membrane-based micro/nano-calorimeters that allow us to measure films weighing micrograms or less from 1-800K and in magnetic fields.

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