Gutenberg Open Science

The Open Science Repository of Johannes Gutenberg University Mainz.

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Recent Submissions

ZeitschriftenaufsatzAccess status: Open Access ,
The impact of a dental technology curriculum and a preventive-clinical curriculum on the development of preclinical preparation skills
(2026)
Morlock, Lisa
;
Morlock, Marius
;
Reuter, Ann Katrin
;
Pfeiffer-Grötz, Thekla J.
;
Deschner, James
Background/Objectives: Fine motor skills are essential for procedural precision in dental education. This study evaluated preparation performance and self-assessed skills among students completing either a dental technology and materials science-based curriculum (DTMS) or a shorter prevention-oriented curriculum (PREV). Assessments were conducted before and after a shared preclinical simulation course. We hypothesized that DTMS students would perform better at baseline and that differences would diminish after the course. Methods: Students in the DTMS and PREV groups prepared a standardized practice block at the beginning and end of a 14-week shared simulation course. Preparations were evaluated for depth, form, and surface smoothness. Students also completed a self-assessment questionnaire using a five-point Likert scale. Results: Sixty-four students participated (68.8% female). At baseline, the PREV group (PREVG) achieved significantly higher overall scores (p = 0.036) and better adherence to preparation form (p = 0.011) than the DTMS group (DTMSG). Following the simulation course, the PREVG showed significant improvements in overall scores (p = 0.009), preparation form (p < 0.001), and surface smoothness (p < 0.001), accompanied by improved self-assessed preparation skills (p = 0.006). In contrast, the DTMSG showed no significant changes in overall scores or individual quality parameters (p > 0.05). Conclusions: A prevention-oriented preclinical curriculum focusing on structured dental procedures was not inferior to a more extensive materials science-based curriculum despite fewer practical exercises. Continuous practice remains essential, while reduced practical workloads may provide curricular capacity for modern interdisciplinary teaching.
ZeitschriftenaufsatzAccess status: Open Access ,
All-optical magnetometric characterization of the exchange-coupled antiferromagnet/ferromagnet system Mn2Au|Ni80Fe20 by terahertz spin-orbit torques
(2026)
Behovits, Yannic
;
Chekhov, Alexander L.
;
Serrano, B. Rosinus
;
Ruge, Amon
;
Reimers, Sonka
Antiferromagnetic materials have great potential for spintronic applications at terahertz (THz) frequencies. However, in contrast to ferromagnets, experimental investigations of antiferromagnets are often challenging due to a lack of straightforward external control of the Néel vector 𝑳 and suitable probes. Here, we study an AFM|FM stack consisting of an antiferromagnetic metal layer (AFM) of the novel material Mn2⁢Au and a ferromagnetic metal layer (FM) of Ni80⁢Fe20. To characterize the AFM|FM stack as a function of the quasistatic 𝑩ext, we perform quasistatic as well as THz-pump magneto-optic probe experiments. Our results demonstrate that AFM and FM are exchange-coupled, and that 𝑳 of the AFM can be set by the simple application of an external in-plane magnetic field 𝑩ext. We identify ultrafast signal components that can consistently be explained by the in-plane antiferromagnetic magnon mode excited by fieldlike Néel spin-orbit torque (NSOT). Remarkably, we find that the 𝑩ext- and THz-pump-induced changes in the optical response of the sample are dominated exclusively by the spin degrees of freedom of AFM. Nonmagnetic signal contributions are minor. We fully calibrate the magnetic circular and magnetic linear optical birefringence of AFM and extract the efficiency of the NSOT. Finally, by selective excitation of domains with different orientations of 𝑳, we are able to determine the relative volume fraction of 0∘, 90∘, 180∘ and 270∘ domains during the quasistatic reversal of 𝑳 by 𝑩ext. Our insights are an important prerequisite for future studies of ultrafast coherent switching of spins by THz NSOT and show that THz-pump magneto-optic-probe experiments are a powerful tool to characterize magnetic properties of antiferromagnets.
ZeitschriftenaufsatzAccess status: Open Access ,
Hot exciton dissociation in graphene nanoribbons
(2026)
Wen, Guanzhao
;
Xu, Fugui
;
Tries, Alexander
;
Zheng, Wenhao
;
Di Virgilio, Lucia
Exciton dissociation in semiconducting nanostructures is crucial for optoelectronic applications, especially when free-carrier generation is required. Despite considerable research, the question of whether and how such generation occurs in strongly excitonic systems remains elusive. Here, we use one-dimensional precision graphene nanoribbons (GNRs) as a model system to investigate exciton dissociation. We systematically explore the interplay between ribbon length (l), excitation energy, and band dispersion in various precision GNRs. Ultrafast Terahertz conductivity measurements reveal that hot exciton dissociation dominates carrier generation, with ribbon length significantly influencing free carrier lifetimes. We identify a critical Bjerrum length (RB) of approximately 20 nm that determines whether photoexcited hot carriers in GNRs can dissociate before forming tightly bound excitons. For shorter ribbons (l < 2RB), rapid ~ps exciton formation prevails. Furthermore, the charge-carrier band dispersion in GNRs plays a critical role in determining dissociation efficiency. Long GNRs with strongly dispersed bands, and consequently low effective carrier masses, exhibit higher mobilities that promote efficient hot-exciton dissociation. These results advance fundamental understanding of dimensionality, energetics, and electronic structure in excitonic materials, providing design principles for optoelectronic devices based on excitonic materials.