arXiv subjects

Paul Kliewer

Publications and source records attributed to Paul Kliewer.

2 recordsLinked to original sources

arXiv2026

Morphology control and low-temperature magnetotransport in chiral 2D perovskite R-(MBA)$_2$PbI$_4$

Two-dimensional chiral hybrid perovskites, such as R/S-(MBA)\textsubscript{2}PbI\textsubscript{4}, are leading candidates for realizing and studying chirality-dependent charge and spin transport. However, their prohibitive in-plane resistance has precluded the electrical characterization. Here, we overcome this bottleneck by engineering the thin-film morphology of the chiral perovskite $R\text{-(MBA)}_2\text{PbI}_4$, enabling the first robust lateral device integration. In Hall-bar geometries, we demonstrate Hall measurements under dark conditions, unambiguously identifying p-type conduction with a Hall mobility of $\sim 0.2 \text{cm}^2 \text{V}^{-1} \text{s}^{-1}$ and a carrier density of $\sim 3\times10^{14} \text{ cm}^{-2}$, parameters previously inaccessible in this class of materials. Furthermore, we observe enhanced magnetoresistance along transport paths crossing grain boundaries, highlighting the strong influence of morphology on in-plane transport. This work demonstrates in-plane magnetotransport, enabling future investigations of the fundamental mechanisms of chirality-induced spin selectivity (CISS) and accelerating the integration of chiral materials into functional spintronic devices.

cond-mat.mtrl-sci↗

arXiv2026

A Cryogenic Uniaxial Strain Cell for Quantum Devices

Mechanical strain is a powerful resource for tuning quantum systems, but existing piezoelectric strain cells are generally optimized for fragile, high-aspect-ratio single crystals rather than the thick, square-profile chips typical of semiconductor quantum devices. Furthermore, adapting these cells for qubits requires accommodating dense RF and DC wiring while maintaining strict electrical isolation from high-voltage piezo actuators. Here, we present a piezoelectric uniaxial strain cell designed to homogeneously strain thick, square-profile substrates. We introduce a highly symmetric dual-chip loading configuration that effectively suppresses flexural deformation and shear stress. The cell integrates a high-density RF/DC interposer to support standard wire bonding and encloses the actuators in a grounded Faraday cage to prevent unwanted Stark shifts in the device layer. Finite element simulations confirm that combining stiff actuators with this symmetric mounting drastically improves strain homogeneity. Finally, we validate the apparatus experimentally by applying uniaxial strain to a 200 $μ$m thick silicon die. Surface strain measurements demonstrate an applied strain of 215 $με$ for 200 V applied piezo bias.

quant-ph↗