arXiv subjects

Julian Zanon

Publications and source records attributed to Julian Zanon.

4 recordsLinked to original sources

arXiv2026

Resolving the band alignment of InAs/InAsSb mid-wave-infrared type-II superlattices

In this work, three InAs/InAs$_{0.65}$Sb$_{0.35}$ superlattices with different periods were investigated using photoluminescence and photoreflectance measurements and their band structure was simulated using a 14 bulk-band kp model. The structures were studied by analyzing the evolution of the spectral features in temperature and excitation power to determine the origin of optical transitions. After identifying which of these are related to the superlattice mini-bands, a rich collection of observed higher-order optical transitions was compared with refractive-index calculations. This procedure was used to adjust the parameters of the theoretical model, namely the bowing parameters of the InAsSb valence band offset and bandgap. It was also shown that the spectroscopy of the higher-order states combined with numerical modeling of the refractive index is a powerful tool for improvement of the material parameters, presenting a new approach to material studies of advanced semiconductor heterostructures.

cond-mat.mtrl-sci↗

arXiv2025

Spatial structure and magnetism of a spin-orbit entangled spin-1 coherent spin center: the manganese neutral acceptor in a III-V semiconductor

A Mn dopant in a III-V semiconductor produces a highly-entangled, coherent triplet ground state not fully captured by single-determinant theories of electron structure. We directly construct an analytic form for its ground-state wavefunction, finding surprising spin-charge correlations not revealed by semiclassical calculations. Spin-correlated circulating currents associated with the dopant yield remarkably large magnetic fringe fields of $\sim$1$\,\mu$T at distances of $\sim 10$~nm from Mn in GaAs, potentially detectable by NV-diamond magnetometry while the dopant spin coherently precesses.

cond-mat.mes-hall↗

arXiv2025

Imaging the Acceptor Wave Function Anisotropy in Silicon

We present the first scanning tunneling microscopy (STM) images of hydrogenic acceptor wave functions in silicon. These acceptor states appear as square ring-like features in STM images and originate from near-surface defects introduced by high-energy bismuth implantation into a silicon (001) wafer. Scanning tunneling spectroscopy confirms the formation of a p-type surface. Effective-mass and tight-binding calculations provide an excellent description of the observed square ring-like features, confirming their acceptor character and attributing their symmetry to the light- and heavy-hole band degeneracy in silicon. Detailed understanding of the energetic and spatial properties of acceptor wave functions in silicon is essential for engineering large-scale acceptor-based quantum devices.

cond-mat.mes-hall↗

arXiv2024

Dual topological insulator with mirror symmetry protected helical edge states

Dual topological insulators (DTIs) are simultaneously protected by time-reversal and crystal symmetries, representing advantageous alternatives to conventional topological insulators. By combining ab initio calculations and the $\mathbf{k}\cdot\mathbf{p}$ approach, here, we investigate the electronic band structure of a Na$_2$CdSn triatomic layer and derive a low-energy $4\times 4$ effective model consistent with all the symmetries of this material class. We obtain the effective Hamiltonian using the L\"owdin perturbation theory, the folding-down technique, and the theory of invariants and determine its parameters by fitting our analytical dispersion relations to those of ab initio calculations. We then calculate the bulk topological invariants of the system and show that the Na$_2$CdSn triatomic layer is a giant-gap (hundreds of millielectronvolts) quasi-two-dimensional DTI characterized by both spin and mirror Chern numbers $-2$. In agreement with the bulk-boundary correspondence theorem, we find that a finite-width strip of Na$_2$CdSn possesses two pairs of counterpropagating helical edge states per interface. We obtain analytical expressions for the edge state energy dispersions and wave functions, which are shown to agree with our numerical calculations. Our work opens an avenue for further studies of Na$_2$CdSn as a potential DTI candidate with room-temperature applications in areas of technological interest, such as nanoelectronics and spintronics.

cond-mat.mes-hall↗