arXiv subjects

Sandra Glotzer

Publications and source records attributed to Sandra Glotzer.

4 recordsLinked to original sources

arXiv2026

AlV$_2$O$_4$ thin films via in-situ interfacial topotaxy

Conventional oxide epitaxy approaches face challenges when the oxidation conditions of constituent elements differ significantly. Here we demonstrate that V--O thin films can serve as solid-phase precursors for epitaxial AlV$_2$O$_4$, comprising a pyrochlore V$^{2.5+}$ network coexisting with AlO$_4$ tetrahedra within the spinel structure. The epitaxial AlV$_2$O$_4$/Al$_2$O$_3$ (0001) heterostructures are realized via interfacial topotactic transformation, involving V--O growth at a moderate temperature followed by in-situ ultra-high-temperature post-annealing to drive a reaction with the Al$_2$O$_3$ substrate. Transmission electron microscopy and temperature-dependent X-ray diffraction analyses reveal excellent structural characteristics that closely reproduce the known charge-ordering transition. This study presents a novel approach to realizing epitaxial structures with convoluted oxidation states where thermodynamic and kinetic barriers would otherwise limit synthesizability.

cond-mat.mtrl-sci↗

arXiv2026

Thermally-Activated Epitaxy of NbO

We demonstrate a thermally-activated epitaxy window for the growth of NbO at temperatures exceeding 1000 $^o$C. NbO films grown in this mode display superior structural and transport properties, which are reproducible across a window of oxygen partial pressure. Through comprehensive analysis, we propose the prototypical electrical properties of NbO, for which a consensus has not yet been made. This study unequivocally demonstrates the utility of high temperatures in the thin film synthesis of refractory metal compounds.

cond-mat.mtrl-sci↗

arXiv2025

Superconducting vacancy-ordered rock-salt NbO films

We report molecular beam epitaxy synthesis of vacancy-ordered rocksalt NbO thin films which display superconductivity. A comparative study of substrates identifies Al$_2$O$_3$ (0001) as the optimal platform for realizing high-quality, single-phase films when growing at temperatures exceeding 1000 $^\circ$C. The controlled NbO films exhibit superconductivity with critical temperatures up to $T_\mathrm{c}$ = 1.37 K, comparable to bulk single crystals. This work addresses the fundamental bottlenecks encountered in the high-temperature epitaxy of compounds with uncommon oxidation states, while expanding the scope of available thin-film superconductors.

cond-mat.supr-con↗

arXiv2024

High temperature diffusion enabled epitaxy of the Ti-O system

High temperatures promote kinetic processes which can drive crystal synthesis towards ideal thermodynamic conditions, thereby realizing samples of superior quality. While accessing very high temperatures in thin-film epitaxy is becoming increasingly accessible through laser-based heating methods, demonstrations of such utility are still emerging. Here we realize a novel self-regulated growth mode in the Ti-O system by relying on thermally activated diffusion of oxygen from an oxide substrate. We demonstrate oxidation selectivity of single phase films with superior crystallinity to conventional approaches as evidenced by structural and electronic measurements. The diffusion-enabled mode is potentially of wide use in the growth of transition metal oxides, opening up new opportunities for ultra-high purity epitaxial platforms based on d -orbital systems.

cond-mat.mtrl-sci↗