William Halperin John Evans Professor of Physics PhD, Cornell University, 1975 Alfred P. Sloan Fellow Yamada Science Foundation Fellow Fellow, American Physical Society Editor, Progress in Low-Temperature Physics Regional Editor for North America for the New Journal of Physics Ultralow Temperature Research Page  |  NMR Research Page William Halperin's research is focused on low-temperature physics (mainly liquid 3He and superconductivity), NMR studies of high-temperature superconductors, and fluid transport in porous media.  In an exciting recent development, his research group has discovered how to produce impurity suppression of the thermodynamic transition of superfluid 3He, thus bringing together the practical aspects of fluid confinement in porous media and the basic science of superfluidity.  Much of this research involves close cooperation and collaboration with Professor Sauls' theoretical group at Northwestern. Halperin has been developing 17O NMR as a probe of the magnetic fluctuations associated with magnetic vortices in novel high-Tc superconductors.  His research group was the first to take these methods to extremely high magnetic fields, above 40 Tesla, using special facilities at the National High Magnetic Field Laboratory in Tallahassee, Florida. Halperin is developing acoustic cavity techniques to investigate collective excitations of the 3He superfluid order parameter and he is investigating gapless superfluidity using high-resolution heat capacity methods applied at very low temperatures.  He is also studying heavy-fermion superconductivity using NMR on crystals of UPt3.  Together with David Seidman of Northwestern's Department of Materials Science and Engineering, Halperin has constructed a facility for crystal growth of heavy-fermion compounds.  Their crystals of UPt3 are of the highest quality ever produced.  In the area of porous media and molecular diffusion, Halperin is using NMR in conjunction with extremely high-gradient magnetic fields to characterize pore structure and heterogeneous diffusion. Selected Publications J. P. Davis, J. Pollanen, H. Choi, J. A. Sauls, and W. P. Halperin Discovery of a New Excited Pair State in Superfluid 3He Nature Physics 4, 571-575 (2008) J. P. Davis, H. Choi, J. Pollanen, and W. P. Halperin Magnetoacoustic Spectroscopy in Superfluid 3He-B Physical Review Letters 100, 015301 (2008) Bo Chen and W. P. Halperin, et al. Two-Dimensional Vortices in Superconductors Nature Physics 3, 239 (2007) J. P. Davis, J. Pollanen, H. Choi, J. A. Sauls, W. P. Halperin, and A. B. Vorontsov Anomalous Attenuation of Transverse Sound in 3He Physical Review Letters, accepted, arXiv:0807.2221v1 (2008) Bo Chen, Sutirtha Mukhopadhyay, W. P. Halperin, Prasenjit Guptasarma, and D. G. Hinks Intrinsic Impurity in the High Temperature Superconductor Bi2Sr2CaCu2O8+d Physical Review B 77, 052508 (2008) J. Pollanen, K. R. Shirer, S. Blinstein, J. P. Davis, H. Choi, T. M. Lippman, L. B. Lurio, and W. P. Halperin Globally Anisotropic High Porosity Silica Aerogels doi:10.1016/j.jnoncrysol.2008.05.047 Penetration Depth and Anisotropy of MgB2 from 11B NMR Bo Chen, Pratim Sengupta, Eric E. Sigmund, and W. P. Halperin, et al. New Journal of Physics 8, 274 (2006) V. F. Mitrovic, E. E. Sigmund, M. Eschrig, H. N. Bachman, W. P. Halperin, A. P. Reyes, P. Kuhns, and W. G. Moulton Spatially Resolved Electronic Structure Inside and Outside the Vortex Core of a High Temperature Superconductor Nature 413, 501 (2001) W. P. Halperin Quantum Size Effects in Metallic Powders Rev. Mod. Phys. 58, 533 (1986)