Gutenberg Open Science
The Open Science Repository of Johannes Gutenberg University Mainz.
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Recent Submissions
Magnetization switching driven by magnonic spin dissipation
(2025) Choi, Won-Young; Ha, Jae-Hyun; Jung, Min-Seung; Kim, Seong Been; Koo, Hyun Cheol; Lee, Oukjae; Min, Byoung-Chul; Jang, Hyejin; Shahee, Aga; Kim, Ji-Wan; Kläui, Mathias; Hong, Jung-Il; Kim, Kyoung-Whan; Han, Dong-Soo
Efficient control of magnetization in ferromagnets is crucial for high-performance spintronic devices. Magnons offer a promising route to achieve this objective with reduced Joule heating and minimized power consumption. While most research focuses on optimizing magnon transport with minimal dissipation, we present an unconventional approach that exploits magnon dissipation for magnetization control, rather than mitigating it. By combining a single ferromagnetic metal with an antiferromagnetic insulator that breaks symmetry in spin transport across the layers while preserving the symmetry in charge transport, we realize considerable spin-orbit torques comparable to those found in non-magnetic metals, enough for magnetization switching. Our systematic experiments and comprehensive analysis confirm that our findings are a result of magnonic spin dissipation, rather than external spin sources. These results provide insights into the experimentally challenging field of intrinsic spin currents in ferromagnets, and open up possibilities for developing energy-efficient devices based on magnon dissipation.
German language adaptation of the Cogniphobia Scale for Headache Disorders (CS-HD) and development of a new short form (CS-HD-6)
(2024) Klan, Timo; Bräscher, Anne-Kathrin; Seng, Elizabeth K.; Gaul, Charly; Witthöft, Michael
Objective:
This study is part of the ODIN-migraine (Optimization of Diagnostic Instruments in migraine) project. It is a secondary, a priori analysis of previously collected data, and aimed to assess the psychometric properties and factor structure of the Cogniphobia Scale for Headache Disorders (CS-HD). We aimed to construct a German-language version and a short version.
Background:
Cogniphobia is the fear and avoidance of cognitive exertion, which the patient believes triggers or exacerbates headache. High cogniphobia may worsen the course of a headache disorder.
Methods:
The 15-item CS-HD was translated into German and back translated in a masked form by a professional translator. Modifications were discussed and carried out in an expert panel. A cross-sectional online survey including the CS-HD and further self-report questionnaires was conducted in a sample of N = 387 persons with migraine (364/387 [94.1%] female, M = 41.0 [SD = 13.0] years, migraine without aura: 152/387 [39.3%], migraine with aura: 85/387 [22.0%], and chronic migraine: 150/387 [38.8%]).
Results:
Exploratory factor analysis resulted in two clearly interpretable factors (interictal and ictal cogniphobia). Confirmatory factor analysis yielded an acceptable to good model fit (χ2(89) = 117.87, p = 0.022, χ2/df = 1.32, RMSEA = 0.029, SRMR = 0.055, CFI = 0.996, TLI = 0.995). Item response theory-based analysis resulted in the selection of six items for the short form (CS-HD-6). Reliability was acceptable to excellent (interictal cogniphobia subscale: ω = 0.92 [CS-HD] or ω = 0.77 [CS-HD-6]; ictal cogniphobia subscale: ω = 0.77 [CS-HD] or ω = 0.73 [CS-HD-6]). The pattern of correlations with established questionnaires confirmed convergent validity of both the CS-HD and the CS-HD-6.
Conclusion:
Both the CS-HD and the CS-HD-6 have good psychometric properties and are suitable for the assessment of cogniphobia in migraine.
Nonisothermal Cahn–Hilliard Navier–Stokes system
(2024) Brunk, Aaron; Schumann, Dennis
In this research, we introduce and investigate an approximation method that preserves the structural integrity of the non-isothermal Cahn–Hilliard–Navier–Stokes system. Our approach extends a previously proposed technique by Brunk and Schumann, which utilizes conforming (inf-sup stable) finite elements in space, coupled with implicit time discretization employing convex-concave splitting. Expanding upon this method, we incorporate the unstable P1|P1 pair for the Navier–Stokes contributions, integrating Brezzi–Pitkäranta stabilization. Additionally, we improve the enforcement of incompressibility conditions through grad–div stabilization. While these techniques are well-established for Navier–Stokes equations, it becomes apparent that for non-isothermal models, they introduce additional coupling terms to the equation governing internal energy. To ensure the conservation of total energy and maintain entropy production, these stabilization terms are appropriately integrated into the internal energy equation.