arXiv subjects

Yilmaz Gul

Publications and source records attributed to Yilmaz Gul.

4 recordsLinked to original sources

arXiv2026

Understanding the superconducting proximity effect in semiconductors through quantum oscillations

Superconductor-semiconductor hybrids host emergent states of matter and offer a platform for new qubits, but the superconducting metal shunts electrical transport, which rules out conventional semiconductor characterization and leaves the hybrid parameters to speculation. Here we determine density, mass, $g$-factor, mobility and subband occupation beneath the superconductor, from Shubnikov-de Haas oscillations of a buried InAs quantum well under Al, Sn, V, Nb, Ta and Re films, with a Dingle analysis that accounts for the shunt. Every metal adds an interface subband whose occupation falls into one of two classes, whereas the mass and $g$-factor of the buried well are unchanged to within 10\%. Within the uncertainty set by the transport mobility, no film shortens the quantum lifetime of the buried well, and Al and Sn lengthen it. Quantum lifetimes bound the hybridization of the interface subband to 2-4~meV. These measurements supply the normal-state parameters that tunnelling spectroscopy renormalizes but cannot measure.

cond-mat.supr-con↗

arXiv2025

Spin-orbit coupling in digital alloyed InGaAs quantum wells

Increasing the spin-orbit coupling in InGaAs quantum wells is desirable for applications involving spintronics and topological quantum computing. Digital alloying is an approach towards growing ternary quantum wells that enables asymmetric interfaces and compositional grading in the quantum well, which can potentially modify the spin-orbit coupling in the quantum well. The spin-orbit coupling of the quantum wells is extracted from beating patterns in the low magnetic field magnetoresistance. Digital alloying is found to modify the spin-orbit coupling by up to 138 meV\textnormalÅ. The changes induced in the spin-orbit coupling can be qualitatively understood as being due to modifications in the interfacial Rashba spin-orbit coupling.

cond-mat.mes-hall↗

arXiv2024

Enhanced mobility of ternary InGaAs quantum wells through digital alloying

High In content InGaAs quantum wells (In $\geq$ 75%) are potentially useful for topological quantum computing and spintronics applications. In high mobility InGaAs quantum wells, alloy disorder scattering is a limiting factor. In this report, we demonstrate that by growing the InGaAs quantum wells as a digital alloy, or a short period superlattice, we can reduce the alloy disorder scattering within the quantum well and increase the peak 2 K electron mobility to 545,000 cm^2/V s, which is the highest reported mobility for high In content InGaAs quantum wells to the best of the authors' knowledge. Our results demonstrate that the digital alloy approach can be used to increase the mobility of quantum wells in random alloy ternary materials.

cond-mat.mes-hall↗

arXiv2020

Experimental evidence for topological phases in the magnetoconductance of 2DEG-based hybrid junctions

While the application of out-of-plane magnetic fields was, so far, believed to be detrimental for the formation of Majorana phases in artificially engineered hybrid superconducting-semiconducting junctions, several recent theoretical studies have found it indeed useful in establishing such topological phases 1-5. Majorana phases emerge as quantized plateaus in the magnetoconductance of the hybrid junctions based on two-dimensional electron gases (2DEG) under fully out-of-plane magnetic fields. The large transverse Rashba spin-orbit interaction in 2DEG, together with a strong magneto-orbital effect, yield topological phase transitions to nontrivial phases hosting Majorana modes. Such Majorana modes are formed at the ends of 2DEG-based wires with a hybrid superconductor-semiconductor integrity. Here, we report on the experimental observation of such topological phases in Josephson junctions, based on In0.75Ga0.25As 2DEG, by sweeping out-of-plane magnetic fields of as small as 0 < B(mT) < 100 and probing the conductance to highlight the characteristic quantized magnetoconductance plateaus. Our approaches towards (i) creation and detection of topological phases in small out-of-plane magnetic fields, and (ii) integration of an array of topological Josephson junctions on a single chip pave the ways for the development of scalable quantum integrated circuits for their potential applications in fault-tolerant quantum processing and computing.

cond-mat.mes-hall↗