Our Research
The Benedek group uses theory and first-principles calculations to design, predict and understand the structures and properties of functional materials, especially complex oxides.
Fundamental Solid-State Chemistry of Complex Oxides and Related Materials
Although a major focus of our research is nonequilibrium materials science, a fundamental understanding of structural and solid-state chemistry lies at the heart of almost all our work. We are particularly interested in the ABO3 perovskite family of oxides (including layered perovskites) shown in the figure below, a large and technologically important family of materials. Recent work has focused on understanding and exploiting new ferroelectric mechanisms to create multifunctional materials.
Publications
- Theory and neutrons combine to reveal a family of layered perovskites without inversion symmetry
- ‘Ferroelectric metals’ reexamined: Fundamental mechanisms and design considerations for new materials
- Understanding ferroelectricity in layered perovskites: new ideas and insights from theory and experiments
- Origin of ferroelectricity in a family of polar oxides: The Dion—Jacobson phases
- Why are there so few perovskite ferroelectrics?
Ultrafast Optical Control of the Functional Properties of Materials
The ability to rapidly create extreme changes in material properties with low light power would have profound consequences for next generation all-optical information processing and for the design of new functional materials, in general. With strongly coupled structural (phonon), electronic, and magnetic degrees of freedom, the complex oxides are a natural material class for realizing this control, and light is the fastest possible external handle. In this project, we work to understand how light can be used to directly manipulate the crystal lattice on ultrafast timescales (nonlinear phononics) to realize hidden or otherwise nonequilibrium phases with novel properties.
Publications
- A strategy to identify materials exhibiting a large nonlinear phononics response: tuning the ultrafast structural response of LaAlO3 with pressure
- Ultrafast control of material optical properties via the infrared resonant Raman effect
- Ultrafast optically induced ferromagnetic/anti-ferromagnetic phase transition in GdTiO3 from first principles
Frontiers of Thermal Transport: Unlocking the Potential of Complex Oxides
Our fundamental understanding of the phonon properties of materials has always lagged behind that of the electronic properties; this knowledge gap severely limits our ability to design materials with target thermal transport properties. This is particularly true of complex oxides. We use first-principles DFT in combination with the phonon Boltzmann transport approach to unravel the microscopic mechanisms of thermal transport in complex oxides, particularly perovskites. A major goal of our work in this area is to establish the fundamental foundation necessary to enable the design of materials with targeted and dynamically controllable thermal transport properties.
Publications
- Understanding mechanisms of thermal expansion in complex oxide thin-films from first principles: Role of high-order phonon-strain anharmonicity
- Strain game revisited for complex oxide thin films: Substrate-film thermal expansion mismatch in PbTiO3
- Thermal expansion in insulating solids from first principles
- Interplay between phonons and anisotropic elasticity drives negative thermal expansion in PbTiO3