James A. Sauls Professor of Physics and Astronomy; Co-Director, Graduate Program in Applied Physics

Research Interests

Sauls' group collaborates with experimental groups at Northwestern (Halperin Lab), Royal Holloway University of London and Institut Néel, CNRS-Grenoble, France that study high-porosity solid-state materials and nano-scale superconducting and magnetic heterostructures for basic and applied research. At Northwestern we have developed new methods utilizing quantum fluids and light scattering for structural studies of high-porosity silica aerogel. These materials are of interest in basic and applied research and have a wide range of applications from detectors to ultra-lightweight insulation. The functionality of spintronics devices are based on the electron's spin in addition to its charge. Sauls' group has developed theoretical proposals for a class of superconducting spintronic devices based on superconducting-ferromagnetic Josephson junctions. We collaborate with experimental groups at Northwestern (Chandrasekhar LabKetterson Lab) to develop novel electronic and spintronic devices for potential use in quantum information technology.

Structure of Silica Aerogel: Aerogel is low density glass (SiO2) formed by a sol-gel process. Our computer simulations illuminate the fractal structure of silica aerogel on scales of 10-5000 nm (read more).

Anomalous Diffusion in Aerogel: The Gossamer-like structure of aerogels leads to non-Gaussian statistics for the distribution exceedingly long free flight paths for particle transport called Lévy Flights (read more).

Superconducting Spintronics: By controlling the electron spin in solid-state heterostructures, spintronics offers a new paradigm for devices with wide ranging functionality. Superconductors can provide new and versatile elements for constructing spintronic devices (read more).

Selected Publications

Chiral Phases of Superfluid 3He in an Anisotropic Medium, Phys. Rev. B, 88, 214503 (2013), J. A. Sauls.

Majorana Excitations, Spin and Mass Currents on the Surface of the Topological Superfluid 3He-B, Phys. Rev. B 88, 184596 (2013), Hao Wu and J. A. Sauls.

Superfluid phases of 3He in a periodic confined geometry, J. Low Temp. Phys. 174, 1-12 (2013), JoshuaWiman and J. A. Sauls.

Collective Modes and Nonlinear Acoustics in Superfluid 3He-B, Vol. 26, 255-311 of Modern Problems in Condensed Matter Physics, Ed. by W. P. Halperin and L. P. Pitaevskii, North-Holland, (original 1990, revised 2013), arXiv::1309.6018 (2013), R. H. McKenzie, J. A. Sauls.

Surface states, edge currents, and the angular momentum of chiral P-wave superfluids, Phys. Rev. B. 84, 214509 (2011), J.A. Sauls.

Thermodynamic potential for superfluid 3He in aerogel, Journal of Low Temperature Physics (Online First), December 10, (2010), S. Ali, L. Zhang and J.A. Sauls.

Theory of heat transport of normal liquid 3He in aerogel, New J. Phys. 12 083056 (2010), J.A. Sauls and P. Sharma.

Theory of spin-transfer torque in superconducting-ferromagnetic nanostructures,Phys. Rev. B78, 174511 (2008), E. Zhao and J.A. Sauls.

Magnetization and spin diffusion of liquid 3He in aerogel, Phys. Rev. B 72, 024507 (2005), J.A. Sauls, et al.