Mona Berciu

Professor

Department of Physics & Astronomy

Research Focus

My current interests focus on developing accurate variational approximations for answering key questions that arise in the study of strongly correlated systems: (i) what are the characteristics of the quasiparticle (polaron) that forms when a charge carrier becomes “dressed” by a cloud of excitations such as phonons, magnons, etc.; (ii) what effective interactions arise between such quasiparticles through exchange of excitations between their clouds; and (iii) what is their combined influence on the properties of the host material. We use these methods to study effective models of materials such as the high-temperature cuprates and iron pnictides, rare-earth nickelates, bismuthates, etc., in a wide region of the parameter space. Such studies supplement numerical exact studies, which are usually rather time consuming and have limitations in terms of system size, temperature range, etc. Our work thus far has been for systems with few-particles (the extremely underdoped limit of insulators) at zero temperature. Very recently, we have made progress on expanding our expertise to cover finite temperatures and finite particle densities.

Current Projects

Effective magnon-mediated interactions between holes doped in a cuprate parent layer
Effective phonon-mediated interactions between particles in systems with Peierls-type electron-phonon coupling
Melting of a bipolaron crystal as a model for insulator-to-metal transition in BaBiO3 and in rare earth nickelates
Properties of polarons at finite temperatures

Selected Publications

S. Johnston, A. Mukherjee, I. Elfimov, M. Berciu, G.A. Sawatzky. Charge disproportionation without charge transfer in the rare-earth nickelates as a possible mechanism for the metal-insulator transition. Phys. Rev. Lett. 112, 106404 (2014).
M. Jiang, M. Berciu, G.A. Sawatzky. Critical nature of the Ni spin state in doped NdNiO2. Phys. Rev. Lett. 124, 207004 (2020).
H. Ebrahimnejad, G.A. Sawatzky, M. Berciu. The dynamics of a doped hole in cuprates is not controlled by spin fluctuations. Nat. Phys. 10, 951 (2014).

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Curtis Berlinguette