Physics Colloquium
Structural control of quantum materials with light
Dr. Ankit S. Disa
Condensed Matter Dynamics Department
Max Planck Institute for the Structure and Dynamics of Matter
Quantum materials exhibit unique macroscopic phenomena with enormous technological potential, ranging from high-temperature superconductivity to topologically protected transport. Hence, at the forefront of condensed matter research is the goal of understanding and controlling their emergent behavior at the smallest length and time scales possible. Due to the strongly intertwined nature of electrons and the crystal lattice in these materials, manipulating the atomic structure allows one to tune interactions and create novel electronic and magnetic phases.
In this talk, I will describe how light can be used to engineer structural distortions in quantum materials on ultrafast time scales, providing a powerful pathway to realize non-equilibrium states of matter, often with functionalities not accessible statically. First, I will illustrate the application of this approach, based on the resonant excitation of optical phonons and terahertz frequencies, to the antiferromagnet CoF2. By exploiting lattice anharmonicities, a transition to a ferrimagnetic phase could be driven with light, whose magnetization is 100-fold larger than the equilibrium limit. Second, I will demonstrate that the coupling of optically driven phonons to long-wavelength strain leads to a metastable ferroelectricity in the quantum paraelectric SrTiO3, with the symmetry-broken state remaining for up to hours after excitation. These experiments provide a basis for the rational design of non-equilibrium functionalities; integrated with targeted materials synthesis, such control promises to unlock new physical phenomena and enable next-generation quantum and ultrafast technologies.
Hosted by Prof. Janko
All interested persons are invited to attend remotely—email physics@nd.edu for information.