SGER: A Non-Conductive Pressure Cell for Pulsed Magnetic Field Experiments in Anisotropic Superconductors

Clark University, Worcester MA

Investigators

Abstract

This Small Grants for Exploratory Research (SGER) project will develop a novel, non-conducting pressure cell for use in pulsed magnetic fields. The miniature gas pressure cell will be designed and built out of plastic or ceramic materials. It will be useful from ambient pressure up to about 3 kbar. This range is very difficult to control with clamp-type cells. There are many important and interesting changes in the properties of electronic materials in this low-pressure range. The cell will be designed for use with a tunnel diode oscillator (TDO), which can be used in arbitrarily small volumes. The TDO apparatus uses an rf signal to probe the penetration depth, resistance, or magnetization of a sample, and works equally well in dc and pulsed magnetic fields. This unique combination of the TDO in a pressure cell will allow detailed studies of the physics of anisotropic organic and heavy fermion conducting systems as a function of pressure. The cell will be used to study how the physical structure of a material affects its electronic structure, and how the electronic structure determines the ground state. In particular, the anisotropic nature of organic and heavy fermion superconductors allows one to eliminate the orbital destruction of superconductivity and to probe the spin coupling or Pauli paramagnetic limit. In this limit the critical magnetic fields are near both the Zeeman energy and the Fermi energy. Both graduate and undergraduate students will be involved in this project. These students will have the experience of working on an exploratory research project. They will also gain the experience of designing and building new apparatus. This Small Grants for Exploratory Research (SGER) project will develop a novel, non-conducting pressure cell that will be useful to study the electronic structure of superconductors. Superconductors are advanced materials that can conduct electricity without losing any of their electrical energy. Superconductors are already used to make the high magnetic fields necessary for MRI imaging in hospitals, and if made more practical, superconductivity would revolutionize the entire electrical power industry. The cell will be designed for use with a tunnel diode oscillator (TDO), which can be used in arbitrarily small volumes. A TDO uses a radio signal to probe the penetration depth, a fundamental property of superconducting materials. The unique combination of the TDO in a pressure cell will allow detailed studies of the physics of anisotropic organic and heavy fermion superconducting systems as a function of pressure. These systems are layered materials that show special properties because of their physical structure. The cell will be used to learn how the physical structure of a material affects its electronic behavior. In particular it will be used to understand how the layered structure of the organic and heavy fermion superconductors makes them behave differently from traditional superconductors. Both graduate and undergraduate students will be involved in this project. These students will have the experience of working on an exploratory research project. They will also gain the experience of designing and building new apparatus.