arXiv subjects

Heike Schlörb

Publications and source records attributed to Heike Schlörb.

4 recordsLinked to original sources

arXiv2026

Identifying open-orbit topological surface states in dual topological semimetal TaSb$_2$

TaSb$_2$, a member of the transition metal dipnictide family of materials, hosts the very rare dual topological phase - weak topological insulating state and topological crystalline insulating state along different crystallographic orientations. So far, studies on the electronic structure of transition metal dipnictides have focused on their overall electronic structure and the bulk open-orbit Fermi surfaces. Using angle-resolved photoemission spectroscopy, density functional theory calculations, and transport measurements, we distinguish the intertwined bulk and surface states on the weakly topological $(20\bar{1})$ plane of TaSb$_2$. We identify multiple electron- and hole-like bulk bands, yielding a near-perfect carrier compensation. Crucially, we observe open-orbit FSs parallel to $\bar{L}$-$\bar{Y}$ direction that are entirely of surface origin. Circular-dichroism ARPES reveals $k \rightarrow -k$ spectral reversal, indicating spin-momentum locking and the topological nature of these surface states. Consistent with this, magnetotransport measurements display weak antilocalization, establishing TaSb$_2$ as a platform for spin-polarized topological transport on a weakly topological surface.

cond-mat.mtrl-sci↗

arXiv2024

In-situ monitoring the magnetotransport signature of topological transitions in the chiral magnet Mn$_{1.4}$PtSn

Emerging magnetic fields related to the presence of topologically protected spin textures such as skyrmions are expected to give rise to additional, topology-related contributions to the Hall effect. In order to doubtlessly identify this so-called topological Hall effect, it is crucial to disentangle such contributions from the anomalous Hall effect. This necessitates a direct correlation of the transversal Hall voltage with the underlying magnetic textures. We utilize a novel measurement platform that allows to acquire high-resolution Lorentz transmission electron microscopy images of magnetic textures as a function of an external magnetic field and to concurrently measure the (anomalous) Hall voltage in-situ in the microscope on one and the same specimen. We use this approach to investigate the transport signatures of the chiral soliton lattice and antiskyrmions in Mn$_{1.4}$PtSn. Notably, the observed textures allow to fully understand the measured Hall voltage without the need of any additional contributions due to a topological Hall effect, and the field-controlled formation and annihilation of anstiskyrmions are found to have no effect on the measurend Hall voltage.

cond-mat.mes-hall↗

arXiv2024

Crystallization Dynamics of Amorphous Yttrium Iron Garnet Thin Films

Yttrium iron garnet (YIG) is a prototypical material in spintronics due to its exceptional magnetic properties. To exploit these properties high quality thin films need to be manufactured. Deposition techniques like sputter deposition or pulsed laser deposition at ambient temperature produce amorphous films, which need a post annealing step to induce crystallization. However, not much is known about the exact dynamics of the formation of crystalline YIG out of the amorphous phase. Here, we conduct extensive time and temperature series to study the crystallization behavior of YIG on various substrates and extract the crystallization velocities as well as the activation energies needed to promote crystallization. We find that the type of crystallization as well as the crystallization velocity depend on the lattice mismatch to the substrate. We compare the crystallization parameters found in literature with our results and find an excellent agreement with our model. Our results allow us to determine the time needed for the formation of a fully crystalline film of arbitrary thickness for any temperature.

cond-mat.mtrl-sci↗

arXiv2024

Lateral Solid Phase Epitaxy of Yttrium Iron Garnet

Solid phase epitaxy is a crystallization technique used to produce high quality thin films. Lateral solid phase epitaxy furthermore enables the realization of non-planar structures, which are interesting, e.g., in the field of spintronics. Here, we demonstrate lateral solid phase epitaxy of yttrium iron garnet over an artificial edge, such that the crystallization direction is perpendicular to the initial seed. We use single crystalline garnet seed substrates partially covered by a SiOx film to study the lateral crystallization over the SiOx mesa. The yttrium iron garnet layer retains the crystal orientation of the substrate not only when in direct contact with the substrate, but also across the edge on top of the SiOx mesa. By controlling the crystallization dynamics it is possible to almost completely suppress the formation of polycrystals and to enable epitaxial growth of single crystalline yttrium iron garnet on top of mesas made from arbitrary materials. From a series of annealing experiments, we extract an activation energy of 3.0 eV and a velocity prefactor of $6.5 \times 10^{14}$ nm/s for the lateral epitaxial crystallization along the <100> direction. Our results pave the way to engineer single crystalline non-planar yttrium iron garnet structures with controlled crystal orientation.

cond-mat.mtrl-sci↗