EPFL bonds perovskite with magnetic substrate to make more efficient hard drive

17 Mar 2020

Forró Group tunes ferromagnet at room temperature with visible light, promising new generation of hard drives.

What do you get when you position a thin film of perovkite material (as used in certain solar cells) on top of a magnetic substrate? The unexpected answer is more efficient hard drive technology. László Forró, a physicist at École Polytechnique Fédérale de Lausanne, (EPFL), and his team say they are "paving the way for the future of data storage."

“The key was to get the technology to work at room temperature,” explained Forró. “We already knew that it was possible to rewrite magnetic spin using light, but you’d have to cool the apparatus to minus 180 degrees Celsius.”

Forró, along with his colleagues Bálint Náfrádi and Endre Horváth, have succeeded at tuning one ferromagnet at room temperature with visible light, which they describe as "a proof of concept that establishes the foundations of a new generation of hard drives that will be physically smaller, faster, and cheaper, requiring less energy compared to today’s commercial hard drives."

A hard drive functions as a data storage device in a computer, where a large amount of data can be stored with an electromagnetically-charged surface. The EPFL team's results are published in the journal PNAS.

Drive demand

Nowadays, the demand for high capacity hard drives has increased more than ever. Computer users are handling larger and larger files, databases, massive image or video files, using more complex software, all of which require a large amount of memory in order to save and process the data as quickly as possible.

The EPFL scientists employ a halide perovskite/oxide perovskite heterostructure in their new method for reversible, light-induced tuning of ferromagnetism at room temperature. Having a perovskite structure represents a novel class of light-absorbing materials.

As reported in PNAS, “The rise of digitalization led to an exponential increase in demand for data storage. Mass-storage is resolved by hard-disk drives, HDDs, due to their relatively long lifespan and low price. HDDs use magnetic domains, which are rotated to store and retrieve information. However, an increase in capacity and speed is continuously demanded.

The paper continues, "We report a method to facilitate the writing of magnetic bits optically. We use a sandwich of a highly light sensitive (MAPbI₃) and a ferromagnetic material (LSMO), where illumination of MAPbI₃ drives charge carriers into LSMO and decreases its magnetism. This is a viable alternative of the long-sought-after heat-assisted magnetic recording (HAMR) technology, which would heat up the disk material during the writing process.”

The method is still experimental, but the team says it may be used to build the next generation of memory-storage systems, with higher capacities and with low energy demands. The method provides a stand for the development of a new generation of magneto-optical hard drives.

Forró concluded, “We are now looking for investors who would be interested in carrying on the patent application, and for industrial partners to implement this original idea and proof of principle into a product.”

All EPFL buildings to be closed until further notice

EPFL this week announced that as of today, Tuesday, March 17th, all EPFL buildings will be closed until further notice: "Students are prohibited from coming to campus. Remote work is mandatory for all EPFL collaborators. This measure is fully justified by the very fast spread of COVID-19 in Switzerland – the number of cases is doubling every two days," states the university's home page.