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O: Fachverband Oberflächenphysik
O 21: Focus Session: Spins on Surfaces studied by Atomic Scale Spectroscopies III
O 21.4: Vortrag
Dienstag, 19. März 2024, 11:30–11:45, MA 004
Unveiling second harmonic resonances in ESR/STM Setups using a time dependent Anderson impurity model. — •Jose Reina Galvez1, Roberto Robles2, Nicolas Lorente2, and Christoph Wolf1 — 1Center for Quantum nanoscience, Seoul, South Korea — 2Centro de Fisica de Materiales, San Sebastian, Spain
The achievement of reproducible single-atom and single-molecule electron spin resonance (ESR) in a scanning tunneling microscope (STM) junction opened new possibilities in the analysis of surface science at the atomic scale [1,2]. The predominant feature of a spin driven on resonance is a resonance at the first harmonic of the Larmor frequency in the current spectrum. Higher harmonic excitations of the spin precession can emerge as long as the driving is sufficiently strong due to nonlinearity in the transport. This leads to a 2nd harmonic resonance at half the Larmor frequency.
In this talk, I will discuss the theoretical aspects of the phenomenon above. Our framework utilizes an open quantum systems formalism for a modified Anderson impurity Hamiltonian where the quantum impurity is connected by time dependent hopping terms to two fermionic baths, a polarized STM tip and a metal substrate [3,4,5]. This barrier modulation in the tunneling allows for efficient driving of the spin-1/2 and the emergence of a 2nd harmonic at driving amplitudes VRF in good agreement with the experiment.
References: [1] S. Baumann et al, Science (2015). [2] S. Kovarik et al, Nano Lett. (2022) [3] J. Reina-Gálvez et al, PRB (2021) [4] J. Reina-Gálvez et al, PRB (2023) [5] https://github.com/qphensurf/
Keywords: Open quantum systems; Simulations; ESR-STM; Transport physics; Qubit