@article{47993, abstract = {{Structural strain severely impacts material properties, such as the linear and nonlinear optical response. Moreover, strain plays a key role, e.g., in the physics of ferroelectrics and, in particular, of their domain walls. μ-Raman spectroscopy is a well-suited technique for the investigation of such strain effects as it allows to measure the lattice dynamics locally. However, quantifying and reconstructing strain fields from Raman maps requires knowledge on the strain dependence of phonon frequencies. In this paper, we have analyzed both theoretically and experimentally the phonon frequencies in the widely used ferroelectrics lithium niobate and lithium tantalate as a function of uniaxial strain via density functional theory and μ-Raman spectroscopy. Overall, we find a good agreement between our ab initio models and the experimental data performed with a stress cell. The majority of phonons show an increase in frequency under compressive strain, whereas the opposite is observed for tensile strains. Moreover, for E-type phonons, we observe the lifting of degeneracy already at moderate strain fields (i.e., at ±0.2%) along the x and y directions. This paper, hence, allows for the systematic analysis of three-dimensional strains in modern-type bulk and thin-film devices assembled from lithium niobate and tantalate.}}, author = {{Singh, Ekta and Pionteck, Mike N. and Reitzig, Sven and Lange, Michael and Rüsing, Michael and Eng, Lukas M. and Sanna, Simone}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, keywords = {{Physics and Astronomy (miscellaneous), General Materials Science}}, number = {{2}}, publisher = {{American Physical Society (APS)}}, title = {{{Vibrational properties of LiNbO3 and LiTaO3 under uniaxial stress}}}, doi = {{10.1103/physrevmaterials.7.024420}}, volume = {{7}}, year = {{2023}}, } @article{22310, author = {{Neufeld, Sergej and Bocchini, Adriana and Schmidt, Wolf Gero}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, title = {{{Potassium titanyl phosphate Z- and Y-cut surfaces from density-functional theory}}}, doi = {{10.1103/physrevmaterials.5.064407}}, year = {{2021}}, } @article{21797, author = {{Riedl, T. and Kunnathully, V. S. and Trapp, A. and Langer, T. and Reuter, Dirk and Lindner, J. K. N.}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, title = {{{Strain-driven InAs island growth on top of GaAs(111) nanopillars}}}, doi = {{10.1103/physrevmaterials.4.014602}}, year = {{2020}}, } @article{15714, author = {{Riedl, T. and Kunnathully, V. S. and Trapp, A. and Langer, T. and Reuter, D. and Lindner, J. K. N.}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, title = {{{Strain-driven InAs island growth on top of GaAs(111) nanopillars}}}, doi = {{10.1103/physrevmaterials.4.014602}}, year = {{2020}}, } @article{34093, author = {{Riedl, Thomas and Kunnathully, V. S. and Trapp, A. and Langer, T. and Reuter, Dirk and Lindner, Jörg}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, keywords = {{Physics and Astronomy (miscellaneous), General Materials Science}}, number = {{1}}, publisher = {{American Physical Society (APS)}}, title = {{{Strain-driven InAs island growth on top of GaAs(111) nanopillars}}}, doi = {{10.1103/physrevmaterials.4.014602}}, volume = {{4}}, year = {{2020}}, } @article{23831, author = {{Baron, Elias and Goldhahn, Rüdiger and Deppe, Michael and As, Donat Josef and Feneberg, Martin}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, title = {{{Influence of the free-electron concentration on the optical properties of zincblende GaN up to 1×1020cm−3}}}, doi = {{10.1103/physrevmaterials.3.104603}}, year = {{2019}}, } @article{13966, author = {{Baron, Elias and Goldhahn, Rüdiger and Deppe, Michael and As, Donat Josef and Feneberg, Martin}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, title = {{{Influence of the free-electron concentration on the optical properties of zincblende GaN up to 1×1020cm−3}}}, doi = {{10.1103/physrevmaterials.3.104603}}, year = {{2019}}, } @article{13406, author = {{Mamiyev, Z. and Lichtenstein, T. and Tegenkamp, C. and Braun, Christian and Schmidt, Wolf Gero and Sanna, S. and Pfnür, H.}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, number = {{6}}, title = {{{Plasmon spectroscopy: Robust metallicity of Au wires on Si(557) upon oxidation}}}, doi = {{10.1103/physrevmaterials.2.066002}}, volume = {{2}}, year = {{2018}}, } @article{4769, abstract = {{In recent years, Raman spectroscopy has been used to visualize and analyze ferroelectric domain structures. The technique makes use of the fact that the intensity or frequency of certain phonons is strongly influenced by the presence of domain walls. Although the method is used frequently, the underlying mechanism responsible for the changes in the spectra is not fully understood. This inhibits deeper analysis of domain structures based on this method. Two different models have been proposed. However, neither model completely explains all observations. In this work, we have systematically investigated domain walls in different scattering geometries with Raman spectroscopy in the common ferroelectric materials used in integrated optics, i.e., KTiOPO4, LiNbO3, and LiTaO3. Based on the two models, we can demonstrate that the observed contrast for domain walls is in fact based on two different effects. We can identify on the one hand microscopic changes at the domain wall, e.g., strain and electric fields, and on the other hand a macroscopic change of selection rules at the domain wall. While the macroscopic relaxation of selection rules can be explained by the directional dispersion of the phonons in agreement with previous propositions, the microscopic changes can be explained qualitatively in terms of a simplified atomistic model.}}, author = {{Rüsing, Michael and Neufeld, Sergej and Brockmeier, Julian and Eigner, Christof and Mackwitz, P. and Spychala, K. and Silberhorn, Christine and Schmidt, Wolf Gero and Berth, Gerhard and Zrenner, Artur and Sanna, S.}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, number = {{10}}, publisher = {{American Physical Society (APS)}}, title = {{{Imaging of 180∘ ferroelectric domain walls in uniaxial ferroelectrics by confocal Raman spectroscopy: Unraveling the contrast mechanism}}}, doi = {{10.1103/physrevmaterials.2.103801}}, volume = {{2}}, year = {{2018}}, } @article{13415, author = {{Braun, Christian and Hogan, Conor and Chandola, Sandhya and Esser, Norbert and Sanna, Simone and Schmidt, Wolf Gero}}, issn = {{2475-9953}}, journal = {{Physical Review Materials}}, number = {{5}}, title = {{{Si(775)-Au atomic chains: Geometry, optical properties, and spin order}}}, doi = {{10.1103/physrevmaterials.1.055002}}, volume = {{1}}, year = {{2017}}, }