Single-Crystalline Micro-Oscillators: Elastic Constants in Strongly Correlated Electron Systems on the Micrometer Scale

The elastic moduli are second derivatives of the free energy with respect to strain, and therefore thermodynamic constants that can probe symmetry breaking at phase transitions. We propose a new measurement technique based on resonant measurements of elastic micro-resonators. By using a Focused Ion Beam (FIB), we cut micro-cantilevers with precisely known orientations and geometries along selected crystal directions from small single crystals. With the FIB, we can create thin cantilevers in the micron scale to explore single domains and domain walls – a capability unique to this technique. These cantilevers are excited by a piezo-electric transducer and the resonance frequencies are detected optically, such that the elastic moduli can be directly calculated from the eigenfrequencies as a function of magnetic field and temperature. This novel technique can provide symmetry-resolved information that is useful in exploring nematicity in materials such as iron-based superconductors and the pseudo-gap in underdoped cuprates. Moreover, finite-element based simulations will be used to determine the elastic constants via the resonance frequencies of various cantilever geometries.