DQMP Forum - Arun Jaiswal - Aishwarya Vishwakarma

12.05.2026 13:00 – 14:00

Quantum geometry induced nonlinear transport in KTaO3 based two-dimensional electron gas
Arun Jaiswal (group of prof. Caviglia)

The quantum geometric tensor (QGT), which defines the geometry of electronic wave functions, is a
fundamental concept that plays a pivotal role in understanding the various intrinsic effects in quantum materials. The imaginary part of QGT, known as the Berry curvature (BC), has been widely explored and is key to explaining the anomalous Hall effect, the family of quantum Hall effects and the concept of topological materials. In contrast, the real part of QGT, known as the quantum metric (QM), has only recently attracted attention and has been established to manifest in phenomena such as flat-band superconductivity, orbital magnetism and nonlinear transport.
In this presentation, I will discuss our recent work on nonlinear transport in the two-dimensional electron gas formed at the surface of KTaO3. Through scaling analysis, we disentangle the contributions of BC and QM and demonstrate that oxide interfaces are a promising platform for exploring QGT-related properties.

[1] Yiyang Jiang et al 2025 Rep. Prog. Phys. 88 076502

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Transport-driven spin dynamics in molecular quantum dots
Aishwarya Vishwakarma (group of prof. Renner)

Spin-dependent charge transport offers a direct route to probing and controlling magnetic moments at the atomic scale. In molecular junctions, spins can be read out by the tunnelling current, while also being driven, polarized, and dephased by the same transport channel. Here, I will discuss organic molecular quantum dots studied with a scanning tunnelling microscope, focusing on charged pentacene molecules on MgO/Ag(001) as a model system with delocalized spin-1/2 states. Radiofrequency excitation enables electron spin resonance at the single-spin level, showing how spin-polarized tunnelling currents can drive
resonant spin dynamics through spin-transfer torque. As a complementary approach, DC magnetoresistance provides an RF-free probe, where field-dependent conductance features contain information on spin interactions, local fields, and decoherence. Our measurements provide access to spin excitation,relaxation, and correlations in single molecules and weakly coupled molecular systems.

[1] S. Kovarik et al., Science 384, 1368-1373 (2024).
[2] A. Vishwakarma et al., in preparation.

Lieu

Bâtiment: Ecole de Physique

Auditoire Stückelberg

entrée libre