A typical CH3NH3(Mn:Pb)I3 perovskite crystal developed by the EPFL researchers. Photo: László Forró/EPFL.Scientists at Ecole Polytechnique Fédérale de Lausanne (EPFL) in France have developed a new perovskite material with unique properties that could be used to build next-generation hard drives.
Storage systems, e.g. hard drives, with higher density and efficiency are required to store the ever greater volumes of data being generated. Such systems require materials whose magnetic properties can be quickly and easily manipulated in order to write and access data on them. EPFL scientists have now developed a perovskite material with a magnetic order that can be rapidly changed without any excess heating. A paper on this work, describing the first ever magnetic photoconductor, appears in Nature Communications.
In the lab of Laszló Forró at EPFL, postdoc Bálint Náfrádi synthesized a ferromagnetic photovoltaic material comprising methylammonium, manganese, lead and iodine (CH3NH3(Mn:Pb)I3). Perovskite photovoltaics are becoming a cheaper alternative to current silicon solar cells, drawing much interest from energy scientists. But the specific perovskite synthesized by Náfrádi exhibits some unique properties that make it particularly interesting as a material for use in next-generation digital storage systems.
Magnetism arises from the interactions between localized and moving electrons in a material, and can be viewed as the result of competition between the different movements of these electrons. This means that the resulting magnetic state is hard-wired in the material and cannot be reversed without changing the material's chemistry or crystal structure. Having an easier way to modify magnetic properties would, however, be incredibly useful for applications such as magnetic data storage.
The new material developed by EPFL scientists provides just such an easier way. "We have essentially discovered the first magnetic photoconductor," says Náfrádi. The crystal structure of the new perovskite 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.
Combining these two properties produced an entirely new phenomenon: the ‘melting’ of magnetization by photoelectrons, which are electrons emitted from a material when irradiated with light. In the new perovskite material, a simple red light-emitting diode (LED) – much weaker than a laser pointer – is sufficient to disrupt, or ‘melt’, the material's magnetic order and generate a high density of traveling electrons. These electrons can be freely and continuously tuned by altering the light's intensity. The timescale for shifting the magnetic order in this material is also very fast, just quadrillionths of a second.
Although still at the experimental stage, with these properties the new material could be used to build the next generation of memory-storage systems, featuring higher capacities with low energy demands. "This study provides the basis for the development of a new generation of magneto-optical data storage devices," says Náfrádi. "These would combine the advantages of magnetic storage – long-term stability, high data density, non-volatile operation and rewriteability – with the speed of optical writing and reading."
This story is adapted from material from EPFL, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.