School of Physics Spring Colloquium Series-Dr. Peter Abbamonte

Speaker: Dr. Peter Abbamonte

Host: Martin Mourigal

Title: Quantum criticality in strange metals

Abstract: In this talk, I will give a common-sense introduction to the topic of strange metals. First observed in copper oxide high-temperature superconductors, the strange metal state is now found in a wide variety of materials, ranging from organic molecular crystals to twisted bilayer graphene. The key feature is Planckian dissipation, where the scattering rate is determined only by fundamental constants, representing a conjectured universal limit on the degree of quantum entanglement possible in a many-body system. I will trace the history of this field, from the marginal Fermi liquid theory to the development of the SYK model by Sachdev and Ye, and Kitaev’s 2014 demonstration that strange metals may be holographic, drawing intriguing parallels to black holes.

Additionally, I will present new momentum-resolved EELS experiments on density fluctuations in the strange metal Bi2Sr2CaCu2O8+x, revealing a quantum critical phase exhibiting conformal invariance—a property that featured prominently in Kitaev’s derivation. Finally, I will discuss evidence for a newly identified excitation, the “scramblon,” which reflects the extreme dissipative nature of these enigmatic materials.

Bio: Peter Abbamonte received his Ph.D. in Physics from the University of Illinois at Urbana-Champaign in 1999, having done his research with Eric Isaacs and Phil Platzman in the Materials Physics Department at Bell Laboratories. He then went to the University of Groningen in The Netherlands on an International Research Fellowship from the National Science Foundation to work with George Sawatzky, and returned to the U.S. as a postdoc in biophysics in Sol Gruner’s group at Cornell University, where he studied photosynthesis in rhodobacter sphaeroides. He joined the scientific staff at Brookhaven National Laboratory in 2003, and was recruited to the University of Illinois in 2005, where he is currently the Fox Family Professor of Engineering in the Department of Physics and an affiliate of the Seitz Materials Research Laboratory.