Quantum materials continue to surprise us with their rich and often unexpected behavior when pushed to their limits. By applying extreme conditions such as high pressure, we can tune their atomic and electronic landscapes in ways that reveal entirely new phenomena. In this talk, I will explore how pressure reshapes the balance between charge density waves (CDWs), superconductivity, and magnetism in two fascinating families of materials: transition metal dichalcogenides (TMDs) and transition metal halides. In TMDs, high pressure unveils a deep connection between CDW order and superconductivity, showing how one phase can give way or even strengthen the other. One striking example is BaFe2Al9, where recent studies reveal a dramatic enhancement of the CDW transition temperature from 110 K to 300 K under pressure the fastest rate ever observed (60 K/GPa). This remarkable behavior runs counter to what we see in conventional CDW materials and points to a unique coupling between lattice strain and electronic instability. In parallel, I’ll discuss how pressure profoundly alters magnetic interactions in transition metal halides, driving these systems into new and sometimes unexpected magnetic states. Together, these results illustrate how high pressure serves as a clean, powerful tool to manipulate quantum matter and unlock phases that remain hidden under ambient conditions.

The non-Hermitian skin effect (NHSE) is a fundamentally distinct phenomenon in non-Hermitian systems, and has no Hermitian analogs. It has lately reshaped the way we understand band structures and topology: the NHSE disrupts the bulk-boundary correspondence between open and periodic boundary conditions’ spectra. How to accurately characterize the NHSE is of importance. Thus, it prompts the development of the generalized Brillouin zone (GBZ) theory. In this talk, I shall introduce modified GBZ theory in non-Hermitian systems without well-defined translational invariance, which captures the influence of disorder, magnetic effects, and non-orientability on the non-Hermitian skin effect. This modified GBZ scheme reveals how the skin effect interacts with disorder or magnetic effects, and how a Möbius-strip configuration alters the skin mode’s localization behavior.
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We have considered the scattering of spin waves by a domain wall (DW) in an easy-axis d-wave altermagnet (e.g. CoF2, MnF2). Similar to the conventional antiferromagnet, the scattering problem is reduced to the Schroedinger equation with sech^2 potential. However, due to altermagnetism, the amplitude of the scattering potential depends on the energy of the magnons. The latter has a number of physical consequences:

(i) the scattering process is different for the clockwise and counterclockwise polarized magnons; (ii) the transmission coefficient is a nonmeromorphic function of the complex-valued wave vector, so a modification of Levinson's theorem is required; (iii) new high-frequency bound (localized) eigenstates appear and propagate along DW. The number of new eigenstates, their eigenfrequencies, and eigenfunctions depend on the altermagnetic strength, wave vector q along DW, and orientation of the DW relative to the crystallographic axes. With the increase of q, the size of the localization region of the bound state can increase as well as decrease, depending on the eigenstate polarization, the sign of the altermagnetic parameter, and the DW orientation.
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Einführung in die Vakuumtechnik - Turbomolekularpumpen - Totaldruckmessröhren - versteckte Lecks, ganztägige Veranstaltung auf Deutsch