Engineering news
Researchers at the École polytechnique fédérale de Lausanne (EPFL) have developed a perovskite material whose magnetic order can be rapidly changed without disrupting it due to heating, described as the first magnetic photoconductor.
The team synthesised a ferromagnetic photovoltaic material that is a modified version of perovskite. Perovskite photovoltaics are gradually becoming a cheaper alternative to current silicon systems, drawing much interest from energy scientists.
Generating more and more data requires storage systems, such as hard drives, with higher density and efficiency. This also requires materials whose magnetic properties can be quickly and easily manipulated in order to write and access data on them.
Magnetism in material arises from the interactions of localised and moving electrons of the material. This means that the resulting magnetic state is wired in the material and cannot be reversed without changing the structure of electrons in the material’s chemistry or crystal structure. An easy way to modify magnetic properties would be an advantage in many applications such as magnetic data storage.
The crystal structure developed at EPFL combines the advantages of both ferromagnets, whose magnetic moments are aligned in a well-defined order, and photoconductors, where light illumination generates high density free conduction electrons.
The combination of the two properties produced a phenomenon of “melting" magnetisation by photo-electrons, which are electrons that are emitted from a material when light hits it. This perovskite material, a simple red LED that is much weaker than a laser pointer, is enough to disrupt the material’s magnetic order and generate a high density of travelling electrons, which can be freely and continuously tuned by changing the light’s intensity. The timescale for shifting the magnetic in this material is also very fast, virtually needing only quadrillionths of a second.
Bálint Náfrádi, a postdoc at EPFL, said: “This study provides the basis for the development of a generation of magneto-optical data storage devices. These would combine the advantages of magnetic storage — long-term stability, high data density, non-volatile operation and re-writability— with the speed of optical writing and reading.”
These properties mean that the material can be used to build the next generation of memory-storage systems, featuring higher capacities with low energy demands.
The study has been published in
Nature Communications.