arXiv subjects

Garima Ahuja

Publications and source records attributed to Garima Ahuja.

3 recordsLinked to original sources

arXiv2026

Local and itinerant orbital contributions to the gyromagnetic response of paramagnetic metals

Orbitronics exploits orbital angular momentum to generate and manipulate angular-momentum currents for controlling magnetisation, offering new approaches to magnetic memory and logic. A quantitative description of this process requires establishing how orbital angular momentum contributes to magnetic moments and, consequently, to the gyromagnetic response that governs magnetisation dynamics. Here, we present a first-principles framework for calculating the effective gyromagnetic tensor (g') of paramagnetic metals, consistently incorporating local and itinerant orbital contributions, spin-orbit coupling, and both state- and occupation-change effects. Applying the framework to V and Pt, we find that orbital paramagnetic responses are comparable to or larger than spin contributions and substantially modify g' from the free-electron value. The atom-centered approximation can underestimate the orbital response by approximately a factor of two, while neglecting occupation changes produces significant errors in the calculated g'. Our calculated g' values for V and Pt agree with experiment, while their pronounced dependence on band filling reveals a route to engineering angular-momentum responses through electronic-structure control. The results establish the modern theory of orbital magnetism as an essential ingredient for describing gyromagnetic response and provide a framework for identifying materials with enhanced orbital functionalities.

cond-mat.mtrl-sci↗

arXiv2026

Properties of 2D Electron or Hole Gases at Tailored s-Si/SiGe Interfaces: A First-Principles Investigation

We have performed first-principles hybrid density functional theory calculations to study the formation and properties of two-dimensional electron or hole gases (2DEG or 2DHG) at s-Si/SiGe interfaces. For small Ge concentrations $x < 0.25$, we find a novel type of band alignment with no offset in the conduction bands, implying that a 2DEG cannot be formed, though a 2DHG can. In contrast, for $x > 0.25$ the band alignment suggests that either a 2DEG or 2DHG can be formed. The electronic band structure features two nearly degenerate 2DEG states at the bottom of the conduction bands, and two 2DHG states at the top of the valence band. These states can be accessed by appropriate doping and gating. Charge density plots of these states show that they feature carriers confined to the near vicinity (2--3 atomic layers) of the interface. Calculated effective masses are anisotropic, being markedly so for the 2DHG states, and in excellent agreement with experiment. This property can be exploited to create a 1D carrier gas. Our results are especially important for s-Si/SiGe-based semiconducting spin qubits for quantum computing applications.

quant-ph↗

arXiv2015

Crowd Congestion and Stampede Management through Multi Robotic Agents

Crowd management is a complex, challenging and crucial task. Lack of appropriate management of crowd has, in past, led to many unfortunate stampedes with significant loss of life. To increase the crowd management efficiency, we deploy automated real time detection of stampede prone areas. Then, we use robotic agents to aid the crowd management police in controlling the crowd in these stampede prone areas. While doing so, we aim for minimum interference by robotic agents in our environment. Thereby not disturbing the ambiance and aesthetics of the place. We evaluate the effectiveness of our model in dealing with difficult scenarios like emergency evacuation and presence of localized congestion. Lastly, we simulate a multi agent system based on our model and use it to illustrate the utility of robotic agents for detecting and reducing congestion.

cs.MA↗