Department of Physics at the University of Illinois at Urbana-Champaign

Peter Abbamonte

Assistant Professor of Physics

Professor Abbamonte received his Ph.D in physics from the University of Illinois at Urbana-Champaign in 1999, after obtaining a bachelor’s degree in physics from the University of Texas, Austin, in 1992. After receiving his Ph.D, he went to the University of Groningen in The Netherlands on a National Science Foundation International Research Fellowship. In 2001, he returned to the U.S. as a postdoc in a biophysics group at Cornell University. In 2003, he moved to Brookhaven National Laboratory as a full-time scientific staff member. He joined the Department of Physics in August of 2005.

Professor Abbamonte is regarded as one of the key originators of the new technique of resonant soft x-ray scattering, which he has applied, among other things, to the study of stripe order in doped Mott insulators and interface effects in oxide devices. This technique is now in use or under commissioning at every major synchrotron facility in the world. He is also known for his solution to the phase problem for inelastic x-ray scattering, which has provided a means to perform real-time imaging of electron motion in condensed matter with attosecond time resolution. Since 2002 he has co-authored eight articles in Science, Nature, and Physical Review Letters.

Research Areas: Electron self-organization in condensed matter, stripe phases, topological order; edge and interface effects in oxide devices; quantum phase transitions; collective excitations in interacting electron systems.

Abbamonte Research Group

Current Research

Our group is dedicated to the study of elementary quantum mechanical processes in condensed matter, including dynamical coupling among electronic and nuclear degrees of freedom, electronic self-organization in systems with competing interactions, and nonlocal screening processes in low-dimensional systems. We employ a variety of momentum-resolved spectroscopic techniques, mainly at modern synchrotron x-ray facilities such as the Advanced Photon Source at Argonne National Laboratory and the National Synchrotron Light Source at Brookhaven National Laboratory.

Striped order in doped Mott insulators
The Mott insulator is the fundamental parent phase of most materials we refer to as "correlated electron systems." If carriers are doped into a Mott insulator (e.g., by removing a spin), there is a competition between their tendency to delocalize—to minimize kinetic energy—and the desire of the system to retain valence bond order.

One of our projects is to study the degree to which this competition tends to drive phase segregation, perhaps into charged magnetic domain lines, colloquially referred to as "stripes." This project is a close collaboration with E. Fradkin.

The figure shows charge correlations indicating the presence of strip order in a doped Mott insulator, measured with resonant x-ray scattering.

Edge and interface states in transition metal oxide devices
The transition metal oxides, most of which are correlated electron systems (usually doped Mott insulators) exhibit many exotic phases.

Even more intricate behavior may be realized, however, near an edge or at the interface between two such systems, where translational symmetry is explicitly broken. This might provide a route to new devices.

The purpose of this project is to explore what new phases exist in heterostructures and patterned arrays of such systems. This project is a close collaboration with the Eckstein group, which grows the structures we use for e-beam patterning and for scattering experiments.

This figure shows superlattice reflections from a heterostructure of LaMnO₃ (top) and SrMnO₃ (bottom). The presence of a reflection at L = 3 indicates that the interfaces are electronically reconstructed.

Quantum phase transitions

It is possible for a system to undergo a change of state, even at zero temperature, as a function of some external parameter such as pressure or applied magnetic field. Such a change cannot be described in terms of a classical balance between energy and entropy because entropy is irrelevant at T = 0.

The purpose of this project is to study how such phase transitions occur, particularly in materials that involve broken translational symmetry such as a charge density wave. We are particularly interested in the behavior of soft modes, and whether in specific cases their dynamics can be tied to the concept of entanglement entropy. This project is done in close collaboration with the Cooper group.

The photograph shows a diamond anvil cell used for x-ray scattering experiments to study the behavior of soft modes through a quantum phase transition.

Collective excitations in interacting systems

A noninteracting system exhibits only single-particle excitations (i.e., electron-hole pairs). If interactions are present, collective excitations may arise that do not necessarily obey Fermi statistics. The simplest example is the “plasmon,” a spin 0 boson excitation of the interacting electron gas, which is responsible for screening in most real materials.

The purpose of this project is to use inelastic x-ray scattering to study collective electronic excitations in various (weakly or strongly) interacting systems. We are particularly interested in applying phase retrieval algorithms to image such excitations in real space and time. This project is a collaboration with the Cahill and Zuo groups in MatSE.

Shown below is an image of the plasmon excitation in pyrolitic graphite, measured with inelastic x-ray scattering. This excitation, which screens charge in this system, is necessary for the existence of Dirac points in graphene.

Selected Publications

S. Smadici, P. Abbamonte, A. Bhattacharya, X. Zhai, B. Jiang, A. Rusydi, J. N. Eckstein, S. D. Bader, J. M. Zuo, "Electronic reconstruction of LaMnO₃-SrMnO₃ superlattice interfaces," Phys. Rev. Lett. 99, 196404 (2007)

A. Rusydi, P. Abbamonte, H. Eisaki, Y. Fujimaki, G. Blumberg, S. Uchida, G. A. Sawatzky, "Quantum melting of the Wigner crystal in the spin ladder of Sr_14-xCa_xCu₂₄O₄₁," Phys. Rev. Lett. 97, 016403 (2006)

P. Abbamonte, A. Rusydi, G. D. Gu, G. A. Sawatzky, D. L. Feng, Charge character of the static ‘stripe’ phase of La_2-xBa_xCuO₄, Nature Physics, 1, (2005)

P. Abbamonte, G. Blumberg, A. Rusydi, A. Gozar, P. G. Evans, T. S. Siegrist, L. Venema, H. Eisaki, E. D. Isaacs, G. A. Sawatzky, Crystallization of charge holes in the spin ladder of Sr₁₄Cu₂₄O₄₁, Nature 431, 1078 (2004)

P. Abbamonte, K. D. Finkelstein, M. D. Collins, S. M. Gruner, Imaging density disturbances in water with a 41.3 attosecond time resolution, Phys. Rev. Lett. 92, 237401 (2004)

P. Abbamonte, L. Venema, A. Rusydi, G. A. Sawatzky, G. Logvenov, I. Bozovic, A structural probe of the doped holes in copper-oxide superconductors, Science 297, 581 (2002)

honors and awards

National Science Foundation International Research Fellowship, 2000
Beckman Fellow, Center for Advanced Study, University of Illinois, 2008