We use micro-Raman spectroscopy to study strain profiles in graphene monolayers suspended over SiN membranes micropatterned with holes of non-circular geometry. We show that a uniform differential pressure load ΔP over elliptical regions of free-standing graphene yields measurable deviations from hydrostatic strain conventionally observed in radially-symmetric microbubbles. The top hydrostatic strain εˉ we observe is estimated to be ≈0.7% for ΔP=1bar in graphene clamped to elliptical SiN holes with axis 40 and 20μm. In the same configuration, we report a G± splitting of 10cm−1 which is in good agreement with the calculated anisotropy Δε≈0.6% for our device geometry. Our results are consistent with the most recent reports on the Gr\"uneisen parameters. Perspectives for the achievement of arbitrary strain configurations by designing suitable SiN holes and boundary clamping conditions are discussed.
@article{arxiv.1606.06995,
title = {Anisotropic straining of graphene using micropatterned SiN membranes},
author = {Fabiana Francesca Settembrini and Francesco Colangelo and Alessandro Pitanti and Vaidotas Miseikis and Camilla Coletti and Guido Menichetti and Renato Colle and Giuseppe Grosso and Alessandro Tredicucci and Stefano Roddaro},
journal= {arXiv preprint arXiv:1606.06995},
year = {2016}
}