Magnetic and Thermodynamic Study of Solid 3He

University Of Florida, Gainesville FL

Investigators

Abstract

This project will investigate magnetic and thermodynamic properties of solid 3H near the nuclear ordering transition. The nuclear magnetism of bulk 3He will be studied as a function of pressure and magnetic field. The magnetic properties of a new form of 3He will also be studied. The new form consists of nanoclusters of 3He that have been precipitated in a matrix of 4He. Surface effects may be significant since an appreciable fraction of he 3He is within a few layers of the surface. Ferromagnetism in the high-pressure hcp phase will be investigated by measuring the frequency spectrum and the magnetization. A companion study at the Hahn-Meitner Institute Berlin will use neutron scattering to characterize the hcp phase, as well as the high magnetic field phase of the low pressure, bcc phase. The critical field for the transition from the high-field phase to the disordered paramagnetic phase will be investigated through the field-dependence of the melting pressure. Graduate students, undergraduates and postdoctoral associates involved in the project will receive training in cutting edge techniques, which prepare them for a range of careers in academe, industry, and government. This project will study the magnetic properties of the helium isotope, 3He, at ultra-low temperatures, where the nuclei of the atoms interact and order themselves in fashion analogous to the way iron atoms couple to form a ferromagnet (though at much higher temperature). The study of 3He at ultralow temperatures can shed light on fundamental magnetism that may have implications for high temperature materials such as iron. There are several different magnetic and structural phases of 3He that occur as a function of pressure and magnetic field. Nuclear magnetic resonance (NMR) and other magnetic techniques will be employed. Another study will look at the magnetic properties of small nanoclusters of 3He that can be formed in a matrix of 4He. These nanoclusters have interesting magnetic properties that depend on their small size and on the interaction of their surface atoms with the surrounding 4He atoms. Collaboration with the Hahn-Meitner Institute in Berlin will combine neutron scattering with low temperature physics techniques to prepare and study the low- and high-pressure nuclear magnetic phases of 3He. Graduate students, undergraduates and postdoctoral associated involved in the project will receive training in cutting edge techniques, which prepare them for a range of careers in academe, industry, and government.