Professor Valles joined the faculty at Brown in 1992. Prior to this he was an Assistant Professor of Physics at the University of Oregon from 1989 to 1992 and a postdoctoral member of the technical staff at AT&T Bell Laboratories from 1987 to 1989. He received his Ph.D. from the University of Massachusetts in 1988 and his Bachelor of Arts from Dartmouth College in 1981. He is the recipient of an Alfred P. Sloan Foundation Fellowship. He is a Fellow of the American Physical Society.
Professor Valles does research in experimental condensed matter physics, in the areas of: superconductivity; electron correlation effects in disordered metals and nanostructures; and in using magnetic fields as a new tool for cell biology and biopolymerization.
Valles' group performs research in two distinct areas: low temperature condensed matter physics and biological physics.
The condensed matter physics research focuses on uncovering and exploring the properties of the possible phases, such as superconducting, insulating, or magnetic, that metals assume at very low temperatures. Which phase emerges in a given system can be determined by a subtle interplay of its geometry, its microscopic structure and whether or not it is in a magnetic field. Most recently, Valles has focused on films of metals that are so thin that they exhibit two dimensional properties. Some of these come with their own nanostructure, while others are patterned with features on the scale of nanometers. The specific topics that this research addresses are the two dimensional superconductor to insulator and superconductor to metal transitions, localization phenomena, proximity effects in mesoscopic systems, and the physics of thin film growth on low temperature and nanostructured substrates.
Biological physics work in the Valles lab has been directed at developing the use of intense, static magnetic fields as a means of manipulating biological systems. They have shown that cell division in frog eggs, the swimming of microorganisms, and biopolymerization phenomena can be modified and investigated with static magnetic fields.
1990-92 Alfred P. Sloan Foundation Fellowship
1991-94 National Science Foundation, "Electron Tunneling Studies of Ultrathin Normal Metal Films"
1991-94 Office of Naval Research, "Electron Tunneling Studies of Ultrathin Films Near the Metal Insulator Transition"
1995-98 Office of Naval Research, "Ballistic Electron-Emission Microscopy Studies of High Tc Superconductor Normal Metal Interfaces"
1995-98 National Science Foundation, "Ultra Low Temperature Transport and Scanning Tunneling Microscopy Studies of Quench Condensed Films"
1997-98 - Salomon Faculty Research Award with Professor K. Mowry -
1998-00 National Science Foundation, "Tunneling and Transport Studies of Ultrathin Films of Metals and Superconductors"
1999-00 National Science Foundation, "Manipulation of Cell Division with Static Magnetic Fields"
2002-04 National Science Foundation, "Quantum Phase Transitions in Nanostructured Superconductors in 2D"
2001-05- NASA, "Magnetic Field Gradient Levitation System for Physics and Biophysics"
2004-2007 NASA, "Microscopic Studies of Gravi-Sensitive Microtubule Assembly in Simulated Variable Gravity Conditions", co-PI with Professor Jay Tang
2005 Jet Propulsion Laboratory "Investigations of the Adaptation of Euglena to Changes in a Simulated Gravity Environment"
2006-2009 National Science Foundation, "Vortices and Quasiparticles in Superconducting Films in Small Order Parameter Amplitude Limit"