Research Expertise and Interest

condensed matter physics and materials science

Research Description

The Frances Hellman research group studies thermodynamic and temperature-dependent properties of materials.

They have developed a series of experiments based on MEMS "lab-on-a-chip" devices utilizing a silicon nitride membrane as a thermal isolation platform which allows them to study orders of magnitude smaller sample sizes than other available thermodynamic measurements such as thin films (as thin as 20nm), nanoparticles, and tiny crystals. Experiments include heat capacity measurements, thermal conductivity and thermopower measurements.

They have modified this membrane-based device into a portable heater stage that is transparent to x-rays for use in in-situ temperature-dependent measurements in facilities that do not support macroscale heating such as sensitive x-ray beamlines at synchrotrons. Their latest development of the device consists in adding a thin biaxially oriented MgO layer for epitaxial growth of thin films on the amorphous silicon nitride membrane.

They study a wide range of materials; current projects include ferromagnetic and antiferromagnetic thin films and nanoparticles, studying the effects of disorder on the magnetic, transport, and thermodynamic properties of magnetic materials and relaxor ferroelectrics, and low temperature thermal properties of amorphous materials.

They currently have openings for graduate students in a variety of projects, including studying the thermodynamics of magnetocaloric materials, multilayer systems, semiconductor nanowires, and various magnetic materials.

For a detailed description of their research including the direction of their magnetic research and their work with heat capacity measurements, visit their group website.