New layer-by-layer built inorganic-organic material enables optical switching of magnetic properties

Credit: Aalto University.

Materials chemists have developed a facile process for piling ultrathin organic and inorganic layers in a pre-designed manner into flexible room-temperature thin-film magnets, whose magnetic properties can be controlled with successive external light illuminations.

In the big data era, photo-controlled room-temperature magnets could open new frontiers for high-density information storage, if these materials could be synthesised from non-critical raw materials and fabricated in device-integrable thin-film form. A group of researchers from the Department of Chemistry and Material Science and the Department of Applied Physics at Aalto University have reported on such materials.

The Millennium Prize awarded ALD technology is modified by the researchers to allow for the deposition of ultrathin photo-switchable organic layers.

The component harnessed by the researchers into these thin films is unique as it has an extremely high magnetic coercivity field, but is at the same time very simple in its chemical composition, being composed of iron and oxygen only.

The team demonstrated the transformation of the straight trans-azobenzene form into the bent cis-azobenzene form when the films were shone with UV and visible light. The structural change between the azobenzene forms was shown to act as an optical switcher for the magnetic properties of the -Fe2O3 layers.

The mechanical flexibility offered by the embedded azobenzene layers is an additional bonus for these films, making them highly attractive material components for the next-generation flexible electronics.

"This is a big step forward, as these new optically controlled thin film magnets with inbuilt flexibility can surpass both the classic rigid inorganic magnets composed of heavy and rare raw materials and the recently highlighted molecular magnets which are fundamentally weaker in their magnetic performance," says Dr. Anish Philip from Aalto University

The current strongly emerging ALD/MLD technique provides us with an elegant way to build these advanced functional materials with atomic-level control. The research group at Aalto is one of the first in this field.

The study was published in a journal.

Anish Philip and his colleagues have published in the Journal of Materials Chemistry C. DOI: 10.1039/D1TC05100H

The new layer-by-layer built organic material enables optical switch of magnetic properties.

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