arXiv subjects

Hemant Arora

Publications and source records attributed to Hemant Arora.

4 recordsLinked to original sources

arXiv2025

Quantum Coulomb Blockade in Orbital Resolved Phosphorus Triple-Donor Molecule

Multi-donor architecture in silicon offers a promising direction towards scalable solid-state qubits and quantum technologies operating at practical conditions. However, the overlap of multiple donor wave-functions develops a complex internal electronic configuration with several discrete energy levels. Probing these discrete-correlated states is essential for understanding inter-donor coupling and exchange interactions towards their practical implementations in quantum-technologies. We have experimentally demonstrated quantum Coulomb blockade mediated systematic filling of several electrons into orbital-resolved molecular states within multi-phosphorous-donor molecules accompanied by a correlated decrement in charging energies for higher hybridized orbitals due to expanded Bohr radii and electron delocalization. Corresponding, first-principle density functional theory calculations offer microscopic insight into the orbital configurations, while the rate equation simulations of quantum Coulomb blockade faithfully reproduce the experimental stability diagrams. This comprehensive characterization advances and discusses the role of donor-molecules in silicon in scalable building blocks for quantum technologies operable at elevated temperatures.

cond-mat.mes-hall↗

arXiv2025

Annealing-Induced Magnetic Modulation in Co- and Y-doped CeO2: Insights from Experiments and DFT

The potential applications of dilute magnetic oxides (DMOs) in magneto-optic and spintronic devices have attracted significant attention, although understanding their magnetic behavior is complex due to intricate interactions of intrinsic defects. The present study aims to investigate the effect of different annealing environments on the magnetic properties of polycrystalline transition metal cation (Co and Y) doped CeO2 DMO with a 5% doping concentration of transition metal (TM). The objective is to investigate the defect interactions within the lattice through a comprehensive investigation involving structural characterizations, magnetic measurements, and first principle calculations. The results show that the Ar/H2 annealing environment induced more oxygen vacancies than air-annealed samples. Consequently, field-dependent magnetization measurements revealed above-room-temperature ferromagnetism (RTFM) in both un-doped and TM-doped CeO2. The ferromagnetic (FM) properties of CeO2 resulted from carrier-trapped vacancy centers facilitating exchange interactions between the spins of magnetic ions. The Langevin field profile indicated that TM-doped CeO2 formed more bound magnetic polarons (BMPs) during annealing in an Ar/H2 environment, which contributed to the enhanced ferromagnetism. Similarly, enhancement in the magnetic properties with increasing oxygen vacancies is observed through first principle calculations. This suggests the potential for optimizing the magnetic properties of DMOs through controlled annealing processes.

cond-mat.mtrl-sci↗

arXiv2024

Room Temperature Spin Filtering and Quantum Transport with Transition Metal-Doped Silicon Quantum Dot

Spin filtering is a fundamental operation in spintronics, enabling the generation and detection of spin-polarized carriers. Here, we proposed and theoretically demonstrated that a 3d transition metal (TM) doped silicon quantum dot (SiQD) is a suitable candidate for spin filter device at room temperature. Using density functional theory (DFT), we investigate the structure, electronic properties, and magnetic behavior of TM-SiQD. Our calculations demonstrate that Mn-doped SiQD exhibits the highest stability. The designed spin-filter device using Mn-doped SiQD shows a spin-filtering efficiency of 99.9% at 300K electrode temperature along with very high conductance. This remarkable efficiency positions it as a promising candidate for room-temperature spintronic devices.

cond-mat.mes-hall↗

arXiv2023

Nitrogen in Silicon for Room Temperature Single Electron Tunneling Devices

Single electron transistor (SET) is an advanced tool to exploit in quantum devices. Working of such devices at room-temperature is essential for practical utilization. Dopant based single-electron devices are well studied at low-temperature although a few devices are developed for high-temperature operation with certain limitations. Here, we propose and theoretically exhibit that nitrogen (N) donor in silicon is an important candidate for effective designing of such devices. Theoretical calculation of density-of-states using semi-empirical DFT method indicates that N-donor in silicon has deep ground state compared to a phosphorus (P) donor. N-donor spectrum is explored in nano-silicon along with the P-donor. Comparative data of Bohr radius of N-donor and P-donor is also reported. The simulated current-voltage characteristics confirm that N-doped device is better suited for SET operation at room-temperature.

cond-mat.mes-hall↗