Tobias Weber Book order

Phase transitions in crystals lead to interesting physical phenomena. This work investigates two systems: First, the effects of the discontinuous orbital ordering transition on the phonon system of the spinel vanadate MgV2O4 . Here, we observe a strong anomalous softening and damping of a transverse-acoustic phonon branch, which we attribute to anharmonic interactions between the phonons and the degenerate orbital electrons. Second, the change of the helimagnon dispersion in the chiral magnet MnSi across the continuous phase transition towards ferromagnetism, for which we observe strong damping effects. Phasenübergänge in Kristallen führen zu interessanten physikalischen Phänomenen. In dieser Arbeit werden zwei Systeme untersucht: Als erstes die Effekte des unstetigen Orbitalordnungs-Übergangs auf das Phononensystem des Spinell-Vanadats MgV2O4 . Hier beobachten wir eine starke anomale Erweichung und Dämpfung eines akustischen Phononenzweigs. Wir führen dies auf anharmonische Wechselwirkungen zwischen den Phononen und den entarteten Orbital-Elektronen zurück. Als zweites System betrachten wir die Entwicklung der Helimagnonen-Dispersion im chiralen Magneten MnSi am stetigen ferromagnetischen Phasenübergang. Hier beobachten wir starke Dämpfungseffekte.

The study explores various models explaining the emergence of linguistic features in English varieties, analyzing five non-standard forms, including dialects, pidgins, and creoles. It evaluates two morphosyntactic and two phonological features, critiquing theoretical approaches and recommending usage-based functionalist models, particularly Bybee's and Ansaldo's frameworks. The work emphasizes functionalist and cognitive universals over formalist approaches, highlighting language contact and speaker interactions as key drivers of language change and evolution.

The study examines various models explaining the emergence of linguistic features in different English varieties, analyzing five non-standard forms, including dialects, pidgins, and creoles. It evaluates morphosyntactic and phonological characteristics, discussing theoretical frameworks and their applicability. The paper favors Bybee's usage-based functionalist approach and Ansaldo's synthesis of new-dialect formation as viable explanations, while rejecting formalist models. It emphasizes the significance of functionalist and cognitive universals in language change, particularly in contexts of language and speaker contact.