arXiv subjects

Moshe Haim

Publications and source records attributed to Moshe Haim.

5 recordsLinked to original sources

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↗

arXiv2025

Resolving the Kagome Origin of the Strange Metallicity in Ni$_3$In

Strong correlations promote singular properties such as strange metallicity, which shows considerable commonality across quantum materials platforms. Understanding the mechanism for such emerging universality is an outstanding challenge, given that the underlying degrees of freedom can be complex and varied. Progress may be made in flat band systems, especially kagome and other frustrated-lattice metals with active flat bands. These systems show strange metal behavior that bears a striking resemblance to what happens in heavy-fermion metals. Here, in scanning tunneling spectroscopy of kagome metal Ni$_3$In, we find a zero-bias peak-dip structure whose variation with magnetic field and temperature tracks the evolution of the strange metal properties. We identify the origin of the peak as compact molecular orbitals formed by destructive interference over the kagome sites, resulting in emergent $f$-shell-like localized moments. Using quasi-particle interference, we visualize their interaction with the Dirac light bands. We thus unveil the essential microscopic ingredients of the $d$-electron-based kagome metals that, while distinct from the atomic orbitals of the $f$-electron-based heavy fermion materials, are responsible for a shared phenomenology between the two types of systems. Our findings provide a new window to uncover and interconnect the essential and yet diverse microscopic building blocks in disparate families of quantum materials that drive a convergence towards a universal understanding in the regime of amplified quantum fluctuations.

cond-mat.str-el↗

arXiv2025

Correlated flat-band physics in a bilayer kagome metal based on compact molecular orbitals

Flat bands, when located close to the Fermi energy, can considerably enhance the influence of electron correlations on the low energy physics in kagome and other frustrated-lattice metals. A major challenge in describing the interaction effects in such bulk materials is that the flat band is often intermixed with a large number of other bands. Here we show that the recently introduced notion of compact molecular orbitals (CMOs) enable a path forward in describing the dominant effect of the Coulomb interactions in spite of the complexity of the bandstructure. Our materials-based analysis allows for the understanding of the scanning-tunneling-microscopy experiment [J. C. Souza et al., preprint (2024)] of the bilayer kagome metal Ni$_3$In in terms of the CMO notion. From the resulting CMO, an effective Anderson lattice model can be set up. This CMO-based approach enables the calculation of correlation effects that is difficult to do based on the atomic orbitals. Furthermore, it suggests an enriched phase diagram for the strange metal physics of the kagome metal, which can be tested by future experiments. We discuss the implications of our results for the general correlation physics of flat band systems and beyond.

cond-mat.str-el↗

arXiv2023

Proximitized insulators from disordered superconductors

We present an experimental study of bilayers of a disordered Ag metal layer close to the metal-insulator transition and an Indium Oxide film which is on the insulating side of the superconductor-insulator-transition. Our results show that superconducting fluctuations within the indium-oxide film, that proximitize the underlying metal layer, induce insulating rather than superconducting behavior. This is ascribed to suppression of density of states (due to the superconducting energy gap) for quasiparticles in the proximitized regions. Our results present a novel manifestation of the proximity effect phenomenon and provide important insight into the nature of the insulating phase of the disorder driven superconductor-insulator-transition.

cond-mat.supr-con↗