TY - JOUR
AB - 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.
AU - Singh, Ekta
AU - Pionteck, Mike N.
AU - Reitzig, Sven
AU - Lange, Michael
AU - Rüsing, Michael
AU - Eng, Lukas M.
AU - Sanna, Simone
ID - 47993
IS - 2
JF - Physical Review Materials
KW - Physics and Astronomy (miscellaneous)
KW - General Materials Science
SN - 2475-9953
TI - Vibrational properties of LiNbO3 and LiTaO3 under uniaxial stress
VL - 7
ER -
TY - JOUR
AB - Coherent nonlinear optical μ-spectroscopy is a frequently used tool in modern material science as it is sensitive to many different local observables, which comprise, among others, crystal symmetry and vibrational properties. The richness in information, however, may come with challenges in data interpretation, as one has to disentangle the many different effects like multiple reflections, phase jumps at interfaces, or the influence of the Guoy-phase. In order to facilitate interpretation, the work presented here proposes an easy-to-use semi-analytical modeling Ansatz, which bases upon known analytical solutions using Gaussian beams. Specifically, we apply this Ansatz to compute nonlinear optical responses of (thin film) optical materials. We try to conserve the meaning of intuitive parameters like the Gouy-phase and the nonlinear coherent interaction length. In particular, the concept of coherence length is extended, which is a must when using focal beams. The model is subsequently applied to exemplary cases of second- and third-harmonic generation. We observe a very good agreement with experimental data, and furthermore, despite the constraints and limits of the analytical Ansatz, our model performs similarly well as when using more rigorous simulations. However, it outperforms the latter in terms of computational power, requiring more than three orders less computational time and less performant computer systems.
AU - Spychala, Kai J.
AU - Amber, Zeeshan H.
AU - Eng, Lukas M.
AU - Rüsing, Michael
ID - 47994
IS - 12
JF - Journal of Applied Physics
KW - General Physics and Astronomy
SN - 0021-8979
TI - Modeling nonlinear optical interactions of focused beams in bulk crystals and thin films: A phenomenological approach
VL - 133
ER -
TY - JOUR
AU - Liu, Ping
AU - Schumann, Nils
AU - Abele, Fabian
AU - Ren, Fazheng
AU - Hanke, Marcel
AU - Xin, Yang
AU - Hartmann, Andreas
AU - Schlierf, Michael
AU - Keller, Adrian
AU - Lin, Weilin
AU - Zhang, Yixin
ID - 48013
JF - ACS Applied Nano Materials
KW - General Materials Science
SN - 2574-0970
TI - Thermophoretic Analysis of Biomolecules across the Nanoscales in Self-Assembled Polymeric Matrices
ER -
TY - CHAP
AU - Schuster, Britt-Marie
AU - Haaf, Susanne
ED - Haaf, Susanne
ED - Schuster, Britt-Marie
ID - 48025
T2 - Historische Textmuster im Wandel. Neue Wege zu Ihrer Erschließung
TI - Fünf Thesen zur Untersuchung des Textsortenwandels
VL - 331
ER -
TY - CHAP
AU - Schuster, Britt-Marie
AU - Thielert, Frauke
AU - Haaf, Susanne
ED - Haaf, Susanne
ED - Schuster, Britt-Marie
ID - 48029
T2 - Historische Textmuster im Wandel. Neue Wege zu ihrer Erschließung
TI - Fragen stellen in Pressetextsorten
ER -
TY - CHAP
AU - Schuster, Britt-Marie
ED - Markewitz, Friedrich
ED - Scholl, Stefan
ED - Schubert, Katrin
ED - Wilk, Nicole M.
ID - 46561
KW - Kommunikationsgeschichte
SN - 9783847116127
T2 - Kommunikative Praktiken im Nationalsozialismus
TI - »Das dankst du deinem Führer« – Adressierungspraktiken in der Widerstandskommunikation gegen den Nationalsozialismus
VL - 3
ER -
TY - CHAP
AU - Biehler, Rolf
AU - Frischemeier, Daniel
AU - Gould, Ronald
AU - Pfannkuch, Maxine
ED - Pepin, Birgit
ED - Gueudet, Ghislaine
ED - Choppin, Jeffrey
ID - 48042
T2 - Handbook of Digital Resources in Mathematics Education
TI - Impacts of Digitalization on Content and Goals of Statistics Education
ER -
TY - BOOK
ED - Schuster, Britt-Marie
ED - Markewitz, Friedrich
ED - Wilk, Nicole M.
ID - 48043
TI - Widerstandshandeln. Sprachliche Praktiken des Sich-Widersetzens zwischen 1933 und 1945
VL - 4
ER -
TY - JOUR
AB - ZusammenfassungDieser Beitrag widmet sich dem Zusammenhang von geistesgeschichtlicher Literaturgeschichtsschreibung und dem Konzept der ›deutschen Bewegung‹. Er rekonstruiert vor allem dessen germanistische Adaption und Weiterentwicklung durch Paul Kluckhohn sowie seinen polyvalenten Einsatz zum heft- und jahrgangsübergreifenden Erzählen einer fortgesetzten nationalen Geistesgeschichte in der Deutschen Vierteljahrsschrift.
AU - Gretz, Daniela
ID - 48047
IS - 3
JF - Deutsche Vierteljahrsschrift für Literaturwissenschaft und Geistesgeschichte
KW - Literature and Literary Theory
KW - Philosophy
KW - Cultural Studies
SN - 0012-0936
TI - »Viele alte Aufgaben wurden damit in einem neuen Lichte gesehen«
VL - 97
ER -
TY - JOUR
AU - Humpert, Lynn
AU - Wäschle, Moritz
AU - Horstmeyer, Sarah
AU - Anacker, Harald
AU - Dumitrescu, Roman
AU - Albers, Albert
ID - 48051
JF - Procedia CIRP
KW - General Medicine
SN - 2212-8271
TI - Stakeholder-oriented Elaboration of Artificial Intelligence use cases using the example of Special-Purpose engineering
VL - 119
ER -