New Phases of Superfluid 3He

Northwestern University, Evanston IL

Investigators

Abstract

****NON-TECHNICAL ABSTRACT**** In this individual investigator project new high frequency acoustic techniques will be employed to explore the structure of 3He superfluids. The goal is to determine the role of impurities and surface conditions on superfluid 3He and to search for new phases that have been predicted to exist. Such effects are particularly easily controlled in 3He but their existence may be general to other related condensed phases such as the high temperature superconductors. Thus the research may have a significant impact on our society. The stabilization of new superfluid states requires synthesis of aerogels, extremely porous but fairly robust glass solids. Local high school and undergraduate students will be involved in this synthesis. Materials will also be provided collaboratively to laboratories in USA, France, and the United Kingdom for a range of applications. Graduate and undergraduate students will obtain training in technically sophisticated techniques including of small angle x-ray scattering, low-temperature methods, and high frequency acoustics. This will prepare them for a range of professional career opportunities with a significant potential impact to our society. ****TECHNICAL ABSTRACT**** This individual investigator award supports a project aimed at understanding the new phases and unusual properties of superfluid 3He that have recently been discovered as a consequence of introducing impurities into the superfluid using high porosity silica aerogels. This project aims to address; "What are the stable phases and what determines the transition from one to another?" The effect of correlations between impurities and the possible stabilization of interesting new states of matter by organizing these impurities with externally imposed global anisotropy will also be explored. Heat capacity and high frequency acoustic measurements will be performed at low-temperatures to investigate the superfluid order parameter and phase stability. Additionally, the basic interactions responsible for, and competing with, superfluidity will be measured. New acoustic cavity methods will be developed and applied to explore newly discovered magneto-acoustic effects and to look for stripe phases that have been predicted to form in thin slabs. This research may impact on our understanding of high temperature superconductivity, and thus future technologies. The silica aerogels will be grown and characterized with the involvement of undergraduate and high school students. Characterization will be performed using the small angle X-ray scattering facilities at the Advanced Photon Source, Argonne National Laboratory. Undergraduate and graduate students will obtain training in technically sophisticated techniques, which will prepare them for a range of professional career opportunities with a significant potential impact on our society.