Quantum many-particle research group

Current members Thomas Vojta Adam Farquhar Chetan Kotabage Man Young Lee Jason Mast Mike Scheetz

Former members Smaine Bekhechi, Postdoc 2000-2001 Mark Dickison, MS 2005 Frank Epperlein, PhD 1999 Bernard Fendler Kevin Heldermon Jose Hoyos, Postdoc 2006-2007 Shellie Huether Kevin Johnson Ryan Kinney Rastko Sknepnek, PhD 2004 Brett Sweeney Torsten Wappler, MS 1996 Clayton Weidinger

Current collaborations Dietrich Belitz (University of Oregon), Jose Hoyos (Duke University), Ted Kirkpatrick (University of Maryland), Rajesh Narayanan (IIT Madras, India), Joerg Schmalian (Iowa State University), Rastko Sknepnek (Iowa State University), Matthias Vojta (University of Cologne, Germany)

Areas of interest quantum and classical phase transitions critical behavior Griffiths singularities strongly correlated electrons magnetism and superconductivity non-Fermi liquids transport in disordered systems metal-insulator transitions non-equilibrium phase transitions Publication list Preprints on the  cond-mat archive
	Sketch of a Griffiths region in a dilute ferromagnet

Pegasus II parallel computer cluster

 Selected Recent Publications

	REVIEW ARTICLES
	Thomas Vojta, Rare region effects at classical, quantum and nonequilibrium phase transitions, J. Phys. A 39, R143-R205 (2006), cond-mat/0602312
	D. Belitz, T.R. Kirkpatrick, and Thomas Vojta, How generic scale invariance influences quantum and classical phase transitions, Rev. Mod. Phys. 77, 579-632 (2005), cond-mat/0403182
	QUANTUM PHASE TRANSITIONS
	Jose A Hoyos and Thomas Vojta, Theory of smeared quantum phase transitions, Phys. Rev. Lett. 100, 240601 (2008), arXiv:0802.2303
	Jose A Hoyos, Chetan Kotabage and Thomas Vojta, Effects of Dissipation on a Quantum Critical Point with Disorder, Phys. Rev. Lett. 99, 230601 (2007), arXiv:0705.1865
	Thomas Vojta and Joerg Schmalian, Percolation Quantum Phase Transitions in Diluted Magnets, Phys. Rev. Lett. 95, 237206 (2005), cond-mat/0508211
	Rastko Sknepnek, Thomas Vojta and Matthias Vojta, Exotic Versus Conventional Scaling and Universality in a Disordered Bilayer Quantum Heisenberg Antiferromagnet, Phys. Rev. Lett. 93, 097201 (2004), cond-mat/0402352
	Thomas Vojta, Disorder-Induced Rounding of Certain Quantum Phase Transitions, Phys. Rev. Lett. 90, 107202 (2003), cond-mat/0212305
	NONEQUILIBRIUM TRANSITIONS
	Thomas Vojta, Adam Farquhar and Jason Mast, Infinite-randomness critical point in the two-dimensional disordered contact process, Phys. Rev. E79, 011111 (2009), arXiv:0810.1569
	Thomas Vojta and Man Young Lee, Nonequilibrium Phase Transition on a Randomly Diluted Lattice, Phys. Rev. Lett. 96, 035701 (2006), cond-mat/0511065
	Thomas Vojta, Broadening of a nonequilibrium phase transition by extended structural defects, Phys. Rev. E 70, 026108 (2004), cond-mat/0402606

 Recent Talks online

	Quantum phase transitions and disorder: Infinite randomness, Griffiths singularities, and smearing APCTP Winter Workshop on Emergent phenomena near quantum critical points, Pohang, Korea, Feb 2007
	Quantum phase transitions on percolating lattices APCTP Winter Workshop on Emergent phenomena near quantum critical points, Pohang, Korea, Feb 2007
	Quantum phase transitions Seminar talk given at the Washington University, St. Louis, March 2006
	Quantum Griffiths effects in itinerant Heisenberg Magnets Short talk given at the 2005 APS March Meeting in Los Angeles
	Rare region effects at a nonequilibrium phase transition Short talk given at the 2005 APS March Meeting in Los Angeles
	Universality of the phase transition in a diluted bilayer Heisenberg antiferromagnet Short talk given at the 2004 APS March Meeting in Montreal
	Itinerant ferromagnetic quantum phase transition Talk given at the ICAM Meeting on Quantum Criticality in Correlated Matter, New York, March 2003
	Disorder-induced rounding of certain quantum phase transitions Short talk given at the 2003 APS March Meeting in Austin
	Unconventional scaling at dirty superconducting quantum phase transitions Talk given at the SPHINX workshop on Unconventional Critical Behavior and Phase Transitions, Prague, September 2002

Quantum phase transitions

Most of our work in recent years has focused on quantum phase transitions. These transitions occur at zero temperature when a non-thermal parameter like the pressure is changed. They are driven by quantum rather than thermal fluctuations. Many of the most exciting discoveries in contemporary condensed matter physics have been attributed to quantum critical points

An elementary introduction is here, a more detailed technical review can be found here.

My Habilitation thesis Quantum phase transitions in electronic systems can be found here. There is also a file containing the introductory chapter only.