Faculty Profile

Portrait
Kristjan Haule
Distinguished Professor
Member of the Graduate Faculty
Group: Condensed matter theory
Phone: 848-445-9032
Office: E267
Email: haule@physics.rutgers.edu
Homepage: http://www.physics.rutgers.edu/~haule/

Research Overview:

URu2Si2 is a very unique material in which the complex electronic matter self-organizes at 17.5K in yet unknown order. A large amount of entropy is lost through the second order phase transition, a proof that there is an order, but the order parameter has newer been directly detected in experiment, hence it is called hidden order. This "hidden order" has been the subject of nearly a thousand scientific papers since it was first reported in 1985 at Leiden University in the Netherlands.

The electronic structure software developed in our group, which is a combination of Dynamical Mean Field Theory and Density Functional Theory (DFT+DMFT), has become much more predictive with invention of the exact "double counting" (see Phys. Rev. Lett. 115, 196403). An important problem, which limited the predictive power of this computational method, was so called double-counting problem. This arrises because both DFT and DMFT account for some part of correlations, but it was not clear unit now what is the common part of correlations accounted by both methods. By the invention of the exact double-counting this ambiguity has been finally set to rest, which makes the predictions of the method much more accurate (for example, the prediction of the total energy of H2 molecule shows only 0.2% error: Phys. Rev. B 91, 155144 (2015).)

Soon after iron superconductors were discovered, we realized that these new superconductors are correlated materials, hosting unconventional superconductivity (PRL 100, 226402 (2008)), and we termed them Hund's metals (arXiv 6 May 2008,published in NJP, see also). In Hund's metals the Coulomb interaction among the electrons is not strong enough to fully localize them, but it significantly slows them down, such that low-energy emerging quasiparticles have a substantially enhanced mass. This enhanced mass emerges not because of the Hubbard interaction U , but because of the Hund’s rule interactions that tend to align electrons with the same spin but different orbital quantum numbers when they find themselves on the same iron atom.

News Item(s):
  • Graduate students Sean Kung and Weilu Zhang, postdoc Verner Thorsmolle, and Profs. Girsh Blumberg and Kristian Haule, working with collaborators in Los Alamos and Leiden University, have made a major step towards solving the 30-years old puzzle of so call
  • Kristjan Haule has haulel been awarded a 2013 Blavatnik Award for Young Scientists from The New York Academy of Sciences
  • Professor Kristjan Haule has been awarded a Rutgers University Board of Trustees Research Fellowship for Scholarly Excellence
  • Kristjan Haule has received the CAREER award from the National Science Foundation
  • Professor Kristjan Haule has been awarded a 2008 Alfred P. Sloan Foundation Fellowship award
  • Board of Governors approved the promotions of Alyson Brooks, Weida Wu, and Kristjan Haule