Rebecca Flint

portrait

Prof. Rebecca Flint

Contact Information

Assistant Professor
Department of Physics and Astronomy
Iowa State University
12 Physics Hall
Ames, IA 50011

Office: Zaffarano A315
Telephone: 515-294-7377
Email: lastname at iastate.edu

I am a condensed matter theorist at Iowa State University, working on various problems in strongly correlated electronic systems. I tend to be interested in translating abstract theoretical ideas to real materials, and vice versa.

I currently have openings in my group both for graduate students and for a postdoctoral researcher. Please feel free to contact me by email for more information.

I was an undergraduate in physics at Caltech, a graduate student in the condensed matter theory group at Rutgers University and most recently a Simons Postdoctoral Fellow in the condensed matter theory group at MIT.

My curriculum vitae.

Research Interests

The search for fundamentally new states of matter is a major driving force in condensed matter, and the peculiar regime between local and itinerant physics is one of the most fruitful places to look. Here, strong electronic correlations realize exotic phases not simply related to free electrons or their Fermi surface instabilities. Instead, these phases are characterized by new broken symmetries or even topological order, and these materials can carry low energy collective modes that fractionalize the electron's charge and spin.

For example, spin liquids are magnetic states that break no symmetries, and yet form a highly correlated topologically ordered state with neutral spin 1/2 excitations. There are now several good spin liquid candidates, but it is necessary to examine how realistic models affect the spin liquid physics. Currently, I am interested in the possible chiral spin liquid in Pr2Ir2O7 and in how to realize the J1-J2 honeycomb lattice spin liquid in real d-electron materials.

Heavy fermion materials also realize a variety of exotic phases; these materials combine electrons from the two extremes: localized electrons, which form magnetic moments or spins, and itinerant electrons, which form a metallic band. At low temperatures, these two species become strongly entangled as the itinerant electrons screen the local moments, effectively melting the spins to form a heavy Fermi liquid. When there are two, competing screening channels instead of one, the two channels ultimately cooperate to melt the spins into an exotic symmetry-breaking phase composite pair superconductivity, which is a purely local mechanism for d-wave superconductivity relevant to the 115 materials, and hastatic order, a time-reversal symmetry breaking phase without any large moments that describes the hidden order in URu2Si2. I am currently working to extend these ideas to Pr based materials.

Publications



My PhD Thesis

PhD Thesis: Symplectic-N in strongly correlated materials
(Click for explanation of symplectic-N)

Strongly correlated electrons provide a unique challenge to theorists as they sit at the intersection of the kinetic and potential energy scales, where traditional, perturbative many body techniques fail. To make progress, we must develop non-perturbative methods. One method that has had some success here is large N theory, which generalizes the number of components of the electron spin from 2 to N, providing an artificial perturbation expansion about a strongly correlated state which, if chosen properly, captures the essential physics. Large N has been heavily used in both the Kondo lattice and in frustrated magnetism, where SU(2N) is the traditional generalization of the electron spin group, SU(2). In choosing the large N group, we chose which symmetries to preserve and which to discard.

Unfortunately, SU(2N) inadvertently loses the time inversion and charge conjugation properties of SU(2); while some generators invert under time reversal like spins, $\vec{S} \rightarrow -\vec{S}$, and remain neutral under charge conjugation, the others behave more like electric dipoles: neutral under time reversal and flipped by charge conjugation. To treat phenomena like frustrated magnetism and superconductivity, which relies on the formation of Cooper pairs, we must restrict ourselves to the subgroup of spin-like generators, SP(2N), a large N limit we call symplectic-N. This limit differs from the SP(2N) limit introduced by Sachdev and Read, which breaks the SU(2N) symmetry of the Hamiltonian down to SP(2N) in that the interaction Hamiltonian is constricted solely from symplectic spins.

Symplectic-N has been successfully applied to frustrated magnetism, where it treats ferromagnetic and antiferromagnetic correlations simultaneously, and to the two channel Kondo model, where it treats the Kondo effect and superconductivity simultaneously. We are currently working to develop symplectic-N Hubbard operators to treat the t-J and Anderson models.


Last updated 21 February 2013