Lead-free magnetic perovskites

Scientists from Linköping University in Sweden, working with the perovskite family of materials, have developed an optoelectronic double magnetic perovskite. The discovery opens up the possibility of coupling spintronics with optoelectronics for fast and energy-efficient information storage.

Perovskites form a family of materials with many interesting properties: they are inexpensive to manufacture, have excellent light-emitting properties, and can be adapted for multiple applications. Researchers have so far focused on developing variants for solar cells, light-emitting diodes and fast optical communication. Perovskites can be made up of many different organic and inorganic substances, but are defined by their special cubic crystalline structure. A type of perovskite that contains halogens and lead has recently been shown to have interesting magnetic properties, opening up the possibility of using it in spintronics.

Spintronics is the field where information about the direction of rotation of a particle (its spin) is stored, not just its charge (more or less). Spintronics is believed to have enormous potential for the next generation of information technologies, as information can be transmitted at higher speeds and with low power consumption. It was found, however, that the magnetic properties of halide perovskites have so far only been associated with lead-containing perovskites, which has limited development of the material for both health and environmental reasons.

Linköping University scientists are now, together with a large group of colleagues in Sweden, the Czech Republic, Japan, Australia, China and the United States, and led by Professor Feng Gao of LiU, have succeeded in creating a non-perovskite alloy. dangerous and produce a double magnetic perovskite.

They show in an article in Advances in science that the magnetic iron ions, Fe₃⁺, are embedded in a previously known double perovskite with interesting optoelectronic properties and composed of cesium, silver, bismuth and bromine, Cs₂AgBiBr₆.

Researchers have shown in experiments that the new material has a magnetic response at temperatures below 30 K (-243.15 ° C).

“These are preliminary experiments of an exploratory investigation and we are not completely sure of the origin of the magnetic response. Our results, however, suggest that it is likely due to a weak ferromagnetic or anti-ferromagnetic response. If so, we have a” whole class of new materials for future information technology. But more research is needed, not least to obtain magnetic properties at higher temperatures, “says Feng Gao.

“Perovskites are exciting materials and have tremendous potential for use in future products that require the fast and inexpensive transfer of information,” he says.