arXiv subjects

Reiley Dorrian

Publications and source records attributed to Reiley Dorrian.

7 recordsLinked to original sources

arXiv2026

Quantum Hall effect in vacancy-engineered $\beta$-Ag$_2$Te

Accessing surface quantum transport in topological insulators is hampered by residual bulk conduction arising from lattice defects. Here, we demonstrate a novel synthesis pathway for realizing high mobility $\beta$-Ag$_2$Te thin films where surface transport is dominant. An \textit{in-situ} vacancy engineering step as part of the molecular beam epitaxy growth process acts to modify the stoichiometry and suppress donor-type defects, enabling continuous tuning of the sheet carrier density over more than an order of magnitude through the charge-neutrality point without an external gate electrode. In the lower-carrier-density films, a fully developed $\nu=1$ quantum Hall state is observed, and Landau-level energies extracted across samples collapse onto the $E_N=v_\mathrm{F}\sqrt{2e\hbar NB}$ relation, providing evidence for the massless Dirac dispersion of the top and bottom surface states. These results establish stoichiometry-driven vacancy engineering as a versatile lithography- and gate-free approach to accessing quantum Hall transport in epitaxial topological-insulator thin films.

cond-mat.mes-hall↗

arXiv2026

Pair-Breaking and Dimensionality in Spin-Orbit Coupled Superconductors

The response of ultra-thin superconducting materials under parallel magnetic fields is often leveraged to obtain insight into the nature of the condensate, including features attributable to unconventional forms of pairing. Despite there being multiple competing mechanisms responsible for suppressing superconductivity, it is common for these analyses to overlook certain depairing channels. Here we report an analysis of thickness dependent superconductivity in thin films of \ce{LaBi2} using the multi-mechanism Kharitonov-Feigel'man framework . By resolving field-enhanced superconductivity in the thin-limit, we obtain an estimate the role of spin exchange scattering, in addition to paramagnetic and orbital effects. Our analyses offer insight into how fundamental quantities such as the critical temperature as well as Pauli limit are defined, recasting the landscape for how scattering times in two-dimensional superconductors can be interpreted.

cond-mat.supr-con↗

arXiv2026

Anisotropic multiband magnetotransport in LaAg$_2$Ge$_2$ thin films

ThCr$_2$Si$_2$-type intermetallics are layered conductors in which crystallographic anisotropy and multiband electronic states often give rise to characteristic magnetotransport phenomena. Here, we report the molecular-beam epitaxy growth of LaAg$_2$Ge$_2$ thin films on MgO(001) and their magnetotransport properties. The Hall effect and magnetoresistance are captured by an effective two-carrier description with a high-mobility electron band, yielding a positive magnetoresistance of 22.5% at 9 T. Angle-dependent magnetoresistance exhibits a dominant twofold anisotropy and additional reproducible dip/peak features at characteristic tilt angles that are nearly independent of field and temperature. These results extend our understanding of the anisotropic electronic transport in thin-film germanides within the ThCr$_2$Si$_2$ family.

cond-mat.mtrl-sci↗

arXiv2026

Relativistic Effects in LaBi$_2$ Thin Films

Chemical substitution in crystalline quantum materials is a powerful way to explore the consequences of strong spin-orbit coupling on their structural and electronic properties. In this work, we present an investigation of thin films of the La$\textit{Pn}_2$ ($\textit{Pn}$~=~Sb, Bi) class of layered square-net intermetallics. We report the growth of LaBi$_2$ with a pristine layer-by-layer growth mode, classifying it as a good metal displaying superconductivity at $\sim$0.55~K. Compared to LaSb$_2$, we attribute the enhanced metallic behavior and improved growth dynamics of LaBi$_2$ to significant relativistic corrections to its electronic band structure and the resulting impact on both surface energy and intrinsic phonon scattering.

cond-mat.mtrl-sci↗

arXiv2026

Field induced superconductivity in a magnetically doped two-dimensional crystal

Magnetic field induced superconductivity is a rare property in nature due to the sensitivity of spin-singlet Cooper pairing to time-reversal symmetry breaking perturbations. However, in rare cases, an interplay between magnetic fields and ions can be engineered to bring about superconductivity at finite fields. Here we use ultra-thin LaSb$_2$ doped with dilute Ce paramagnetic impurities to demonstrate a magnetic field-induced superconducting dome in a two-dimensional crystal. The reduced dimensionality of the structure enables the use of an in-plane magnetic field to dynamically suppress spin fluctuations on the Ce-site, which leads to an anomalous enhancement of the critical temperature with increasing field. By modelling the spin scattering dynamics across the experimental parameter space, we reveal insight into the complex nature of paramagnetic impurities in magnetic fields at low temperature, and how their manipulation can result in the ability to tune between competing magnetic pair-breaking regimes. Realizing this physics in a two-dimensional crystalline setting invites the application of similar approaches to unconventional forms of superconductivity while also highlighting new experimental standards which should be employed when studying ultra-thin materials in general.

cond-mat.supr-con↗

arXiv2025

Stacking-Selective Epitaxy of Rare-Earth Diantimonides

Deterministic control of the layering configuration of two-dimensional quantum materials plays a central role in studying their emergent electronic properties. Here we demonstrate in-situ control over competing stacking configurations in thin film crystals of the rare-earth diantimonides by synthesizing in proximity to competing structural orders. A crossover between the epitaxially stabilized monoclinic structure and the orthorhombic structure commonly observed in bulk crystals is navigated through three axes; the relative cation/anion ratio, growth temperature, and choice of lanthanide ion, culminating with a comparative magnetotransport study of single-yet-distinct phase CeSb2 films. These results set the stage for an expanded search for hidden stacking configurations in layered compounds which have evaded detection.

cond-mat.mtrl-sci↗

arXiv2024

Monoclinic LaSb$_2$ Superconducting Thin Films

Rare-earth diantimondes exhibit coupling between structural and electronic orders which are tunable under pressure and temperature. Here we present the discovery of a new polymorph of LaSb$_2$ stabilized in thin films synthesized using molecular beam epitaxy. Using diffraction, electron microscopy, and first principles calculations we identify a YbSb$_2$-type monoclinic lattice as a yet-uncharacterized stacking configuration. The material hosts superconductivity with a $T_\mathrm{c}$ = 2 K, which is enhanced relative to the bulk ambient phase, and a long superconducting coherence length of 140 nm. This result highlights the potential thin film growth has in stabilizing novel stacking configurations in quasi-two dimensional compounds with competing layered structures.

cond-mat.mtrl-sci↗