SKM 2023 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 8: Ultrafast Magnetization Effects I

MA 8.1: Hauptvortrag

Montag, 27. März 2023, 15:00–15:30, HSZ 04

Optical control of antiferromagnetism — •Christian Tzschaschel — Department of Chemistry and Chemical Biology, Harvard University, USA

Antiferromagnets are a promising class of materials for novel spintronic applications. The absence of a net magnetization not only leads to a robustness of the magnetic state against magnetic fields but may also enable faster and potentially more energy efficient switching dynamics compared to their ferromagnetic counterparts. However, probing and controlling an antiferromagnetic state, in particular on ultrafast timescales, is a major challenge of antiferromagnetic spintronics.

Here, we will exploit magneto-optical and inverse magneto-optical effects to control antiferromagnetism. For example, the inverse Faraday effect, whereby circularly polarized light acts as a magnetic field in a material, allows us to selectively excite specific magnon modes in fully compensated antiferromagnets. The excitation mechanism can be based on a rotation of the antiferromagnetic vector or the generation of a net magnetization in the material. We will show that excitation mechanisms that induce a net magnetization exhibit a significantly higher efficiency. Moreover, we uncover a new inverse magneto-optical effect that allows us to deterministically induce an antiferromagnetic state in a magneto-electric antiferromagnet.

Our results demonstrate a high degree of optical control of antiferromagnetism, where we use light as both a probe and a handle to act on an antiferromagnetic state. We thus move closer to achieving a fundamental requirement for future ultrafast opto-spintronic devices.