Experimental Studies at Ultralow Temperatures

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9623716 Bozler This project is an investigation of three different materials at ultralow temperatures while developing advanced dc SQUID amplifiers to support this work. The first study is of the magnetic properties of superfluid 3He, focusing on the discrepancy between SQUID and NMR measurements of the static susceptibility. The second study is of thin films of 3He in magnetic fields sufficiently small that a wo-dimensional nuclear ferromagnetic transition can be manifested. In these magnetic fields, conventional NMR techniques are unusable. Finally, electrical conduction in reduced dimensionality systems will be studied, including the physics of disorder in artificial two-dimensional networks of effectively one-dimensional wires. %%% This project is a study of materials at ultralow temperatures combined with, and supported by, the development of ultralow temperature experimental techniques, including advanced low-noise amplifiers. At temperatures near 1 mK (0.001 degrees above Absolute Zero) the rare isotope of helium (helium-3) changes to a superfluid whose magnetic properties are not yet well understood. These magnetic properties will be studied in this project. Thin films of liquid helium-3 will also be studied because they have proved to be an excellent model for magnetism in two dimensions. Artificial one- and two-dimensional metallic systems will be manufactured and studied to better understand the role of disorder in natural physical systems. ***