Who
Damjan Pelc (University of Zagreb)
Abstract
Quantum materials display a wide range of interesting dynamical phenomena, from soft phonon
modes to spin and charge excitations, and the study of dynamical properties can yield profound
insight into the physics of these systems. Many important types of excitations couple to light,
and can thus be investigated using optical spectroscopy. Yet the relevant energy scales in several
prominent material systems are in the meV range, where optical spectroscopy becomes
challenging. The most commonly used experimental approach is time-domain THz spectroscopy,
a powerful technique that has been extensively used in studies of quantum materials. Yet time-
domain measurements are typically limited to energies above ~1 meV, and are difficult to
perform in materials with high reflection coefficients. In this talk, I will describe a novel
approach to infrared spectroscopy at sub-THz frequencies developed in my group, that enables
sensitive optical absorption measurements in highly reflecting samples. The technique bridges
the gap between microwave spectroscopy and established time-domain methods, and enables
experiments that probe both charge and spin degrees of freedom. I will discuss several examples:
our recent observation of spin-phonon hybridized modes in metallic strontium titanate,
measurements of zero-field antiferromagnetic resonance in layered van der Waals magnetic
systems, and studies of the low-energy optical response in candidate topological superconductors
based on SnTe.
modes to spin and charge excitations, and the study of dynamical properties can yield profound
insight into the physics of these systems. Many important types of excitations couple to light,
and can thus be investigated using optical spectroscopy. Yet the relevant energy scales in several
prominent material systems are in the meV range, where optical spectroscopy becomes
challenging. The most commonly used experimental approach is time-domain THz spectroscopy,
a powerful technique that has been extensively used in studies of quantum materials. Yet time-
domain measurements are typically limited to energies above ~1 meV, and are difficult to
perform in materials with high reflection coefficients. In this talk, I will describe a novel
approach to infrared spectroscopy at sub-THz frequencies developed in my group, that enables
sensitive optical absorption measurements in highly reflecting samples. The technique bridges
the gap between microwave spectroscopy and established time-domain methods, and enables
experiments that probe both charge and spin degrees of freedom. I will discuss several examples:
our recent observation of spin-phonon hybridized modes in metallic strontium titanate,
measurements of zero-field antiferromagnetic resonance in layered van der Waals magnetic
systems, and studies of the low-energy optical response in candidate topological superconductors
based on SnTe.