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MM: Fachverband Metall- und Materialphysik

MM 18: Poster Session I

MM 18.24: Poster

Montag, 16. März 2020, 18:15–20:00, P4

Theoretical Description of Non-linear Processes in magnetic material — •Shalu Rani and Valérie Veniard — École Polytechnique, Institute Polytechnique de Paris, Palaiseau, France

Chromia is an anti-ferromagnetic insulator and an ideal material to demonstrate ultra-fast control of demagnetization at higher speed. Ultra-fast control on magnetic state could have the strong impact on magnetic recording technology.

Second harmonic generation (SHG) is used to study the optical properties of materials. SHG is forbidden in centro-symmetric materials and it is possible to obtain a structural and electronic characterization for these systems. However, the absence of time-inversion symmetry in antiferromagnetic materials leads to new contributions in second harmonic generation, thus revealing the arrangement of spins in the solid. SHG becomes a powerful tool to study of ultra-fast demagnetization processes. Chromia is centrosymmetric, but SHG occur because symmetry broke due to the spin.

There are few satisfactory theoretical descriptions for SHG in magnetic materials, since spin-orbit coupling, electron-electron interactions and local field effect must be treated on the same footing. The project is to calculate the Second order response function of chromia using Time-Dependent Density Functional Theory, and taking into account the many-body effects through an exchange-correlation kernel derived from the Bethe-Salpeter equation (BSE) for the linear response.

Results will be shown for the linear response, the GW corrected band gap for the Chromia and for the BSE calculations