Staff directory Zeila Zanolli

Zeila Zanolli

Senior Postdoctoral Researcher
RYC
zeila.zanolli(ELIMINAR)@icn2.cat
Theory and Simulation

Publications

2019

  • Spin States Protected from Intrinsic Electron-Phonon Coupling Reaching 100 ns Lifetime at Room Temperature in MoSe2

    Ersfeld M., Volmer F., De Melo P.M.M.C., De Winter R., Heithoff M., Zanolli Z., Stampfer C., Verstraete M.J., Beschoten B. Nano Letters; 19 (6): 4083 - 4090. 2019. 10.1021/acs.nanolett.9b01485. IF: 12.279

    We present time-resolved Kerr rotation measurements, showing spin lifetimes of over 100 ns at room temperature in monolayer MoSe2. These long lifetimes are accompanied by an intriguing temperature-dependence of the Kerr amplitude, which increases with temperature up to 50 K and then abruptly switches sign. Using ab initio simulations, we explain the latter behavior in terms of the intrinsic electron-phonon coupling and the activation of transitions to secondary valleys. The phonon-assisted scattering of the photoexcited electron-hole pairs prepares a valley spin polarization within the first few ps after laser excitation. The sign of the total valley magnetization, and thus the Kerr amplitude, switches as a function of temperature, as conduction and valence band states exhibit different phonon-mediated intervalley scattering rates. However, the electron-phonon scattering on the ps time scale does not provide an explanation for the long spin lifetimes. Hence, we deduce that the initial spin polarization must be transferred into spin states, which are protected from the intrinsic electron-phonon coupling, and are most likely resident charge carriers, which are not part of the itinerant valence or conduction band states. © 2019 American Chemical Society.


2018

  • Hybrid quantum anomalous Hall effect at graphene-oxide interfaces

    Zanolli Z., Niu C., Bihlmayer G., Mokrousov Y., Mavropoulos P., Verstraete M.J., Blügel S. Physical Review B; 98 (15, 155404) 2018. 10.1103/PhysRevB.98.155404. IF: 3.813

    Interfaces are ubiquitous in materials science, and in devices in particular. As device dimensions are constantly shrinking, understanding the physical properties emerging at interfaces is crucial to exploit them for applications, here for spintronics. Using first-principles techniques and Monte Carlo simulations, we investigate the mutual magnetic interaction at the interface between graphene and an antiferromagnetic semiconductor BaMnO3. We find that graphene deeply affects the magnetic state of the substrate, down to several layers below the interface, by inducing an overall magnetic softening, and switching the in-plane magnetic ordering from antiferromagnetic to ferromagnetic. The graphene-BaMnO3 system presents a Rashba gap 300 times larger than in pristine graphene, leading to a flavor of quantum anomalous Hall effect (QAHE), a hybrid QAHE, characterized by the coexistence of metallic and topological insulating states. These findings could be exploited to fabricate devices that use graphene to control the magnetic configuration of a substrate. © 2018 American Physical Society.