Edanel Fishbein | Searcharxiv

arXiv2026

Discovery of New Zintl Films and Nanowires Grown by Topotaxy Conversion of III-V Semiconductors

Zintl phases draw broad interest for their diverse structural, magnetic, thermoelectric, topological and optical properties. Recently, Zintl Eu$_3$In$_2$As$_4$ and Eu$_5$In$_2$As$_6$ nanowires with axion magneto-topology have been synthesized by molecular beam epitaxy via topotactic conversion of InAs wurtzite and zincblende nanowires. Here we extend this methodology, demonstrating that topotaxial mutual-exchange growth applies not only to a broader set of III-V semiconductors beyond InAs but also to three-dimensional substrates whose surfaces are converted into Zintl thin films, as well as to nanowires. We report the growth of two new compounds: Eu$_5$Ga$_2$As$_6$ thin films converted from GaAs substrates, and Eu$_5$Al$_2$As$_6$ thin films from AlAs films. We also convert GaAs nanowires of both wurtzite and zincblende structures into Eu$_5$Ga$_2$As$_6$ nanowires. Though the stoichiometry is the same as in the previously reported Eu$_5$In$_2$As$_6$ case, microscopy and diffraction reveal a single-phase Pnma symmetry group rather than Pbam, highlighting symmetry-guided topotactic pathways to new Zintl frameworks. The compounds host an intricate magnetic phase diagram with three magnetic transitions, including two distinct antiferromagnetic orders and a canted antiferromagnetic phase that evolves into another antiferromagnetic phase under applied field through a spin-flop transition. Ab initio calculations predict that both Zintls are semiconductors with gaps of 0.79 eV in Eu$_5$Ga$_2$As$_6$ and 0.90 eV in Eu$_5$Al$_2$As$_6$. The lower symmetry and increased structural complexity suggest suppressed lattice thermal conductivity, pointing to thermoelectric potential alongside prospects in spintronics and detector technologies. These results give an epitaxy-compatible route for discovering and integrating magnetic Zintl thin films and nanowires directly from relevant III-V semiconductors.

cond-mat.mtrl-sci↗

arXiv2026

Competing incommensurability, electronic correlations, and superconductivity in a hybrid transition metal dichalcogenide

The engineering of superlattices in two-dimensional van der Waals materials has enabled the realization of rich phase diagrams hosting topological and strongly correlated phases. While incommensurability is widespread in three-dimensional systems, the role of moir\'e potentials in bulk materials remains largely unexplored. Here, using scanning tunneling microscopy, we demonstrate that a bulk transition-metal dichalcogenide polytype, 4Hb-TaS$_2$, hosts an emergent incommensurate potential between its alternating 1T and 1H layers. Interplay with a concomitant incommensurate charge-density wave suppresses the long-range order of this potential, leading to intricate coupling with electronic correlations in the doped 1T surface layer. Combining density functional theory with dynamical mean-field theory, we show that the lattice mismatch locally modulates the interlayer distance, thereby tuning both hybridization and charge transfer between the correlated 1T and metallic 1H layers. This redistribution of charge drives the system towards a doped Mott regime, in which the remaining local moments become self-screened, giving rise to a zero-bias resonance. We further find that bulk superconductivity competes with both the underlying landscape and the associated charge transfer. Our results establish incommensurate potentials as a previously overlooked ingredient in hybrid transition-metal dichalcogenides, highlighting their central role in the interplay between electronic correlations, charge-density-wave order, and unconventional superconductivity.

cond-mat.str-el↗