arXiv subjects

Eric Herrmann

Publications and source records attributed to Eric Herrmann.

3 recordsLinked to original sources

arXiv2026

Deterministic Realization of Complex Local Strain Fields and Bandgap Profiles in Two-Dimensional Materials

Emerging classical and quantum device concepts demand precise spatial control over the optoelectronic properties of two-dimensional (2D) materials, but deterministic engineering via local multiaxial strain distributions remains challenging. Using Ga$_2$Se$_2$, we demonstrate a material-agnostic platform in which nanostructure geometry deterministically prescribes in-plane strain profiles in suspended van der Waals membranes. We first use hyperspectral photoluminescence mapping and experimentally-constrained finite element analysis to quantify the experimental biaxial and uniaxial strain gauge factors that relate strain to the change in bandgap. We next show that a two-component analytical model can predict, with less than 12% error, spatially-resolved bandgap shifts arising from multiaxial strain distributions in complex geometries, including the interactions between adjacent nanostructures. Finally, we demonstrate that this approach can be extended to other materials. The results demonstrate that nanostructure design provides a quantitative, deterministic framework for the realization of designed strain and bandgap distributions in 2D materials.

cond-mat.mtrl-sci↗

arXiv2026

Quantifying the Relationship Between Strain and Bandgap in Thin Ga$_2$Se$_2$

We present a rigorous analysis that combines theory, simulation, and experimental measurements to quantify the relationship between strain and bandgap in two dimensional gallium selenide (Ga$_2$Se$_2$). Experimentally, we transfer thin Ga$_2$Se$_2$ flakes onto patterned substrates to deterministically induce multiaxial localized strain. We quantify the local strain using a combination of atomic force microscopy (AFM) measurements and COMSOL Multiphysics simulation. We then experimentally map the strain-induced bandgap shifts using high-resolution hyperspectral PL imaging to generate a robust and statistically significant dataset. We systematically fit this data to extract gauge factors that relate the bandgap shift to the local uniaxial and biaxial strain. We then compute the uniaxial and biaxial strain gauge factors via density functional theory (DFT) and find excellent agreement with the experimentally-determined values. Finally, we show that a simple model that computes bandgap shifts from the local uniaxial and biaxial strain predicts the observed multiaxial bandgap shift with less than 10\% error. The combined results provide a framework for deterministic realization of tailored bandgap profiles induced by controlled strain applied to Ga$_2$Se$_2$, with implications for the future realization of localized quantum emitters for quantum photonic applications.

cond-mat.mtrl-sci↗

arXiv2025

Reversible local strain engineering of $\mathrm{WS}_2$ using a micro-mechanical spring

Local strain engineering is a promising technique to tune the properties of two-dimensional materials at the nanoscale. However, many existing methods are static and limit the systematic exploration of strain-dependent material behavior. Here, we demonstrate dynamic and reversible control of local strain distributions in suspended trilayer tungsten disulfide ($\mathrm{WS}_2$) via nanoindentation using a micro-mechanical spring patterned with nanoscale probes. Micro-photoluminescence measurements reveal that indentation using a ring-shaped probe induces a nearly uniform biaxial strain distribution accompanied by a reversible redshift of the neutral exciton peak, consistent with simulated strain magnitudes. We further show that the in-plane strain distribution is spatially programmable by engineering the probe geometry and present designs for inducing point-like, uniaxial, biaxial, and triaxial strain distributions. The presented platform enables substrate-free, repeatable local strain engineering in suspended 2D materials and provides a versatile tool for streamlining the investigation of strain-dependent phenomena.

cond-mat.mtrl-sci↗