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An unconventional 2D ferromagnet might enable smaller and more reliable devices for data storage.

Theoretical calculations by KAUST researchers have identified a material that could improve magnetic data-storage devices. This material consists of three atomic layers and could lead to more minor and reliable magnetic tunnel junctions (MTJs).

MTJs contain two ferromagnetic layers separated by a thin insulating barrier, which enables them to sense magnetization. They are used, for example, to read data from hard disk drives that store the zeroes and ones of binary information in the magnetization of tiny regions on its disk.

MTJs also form the basis of a data storage technology called magnetic random-access memory, which is used in applications where data must be read or written rapidly or when high endurance is required. In these MTJs, one of the ferromagnetic layers has a fixed magnetization, while the magnetization of the other can point in the same or the opposite direction. These two states encode the binary information. Data is written by switching the magnetization, and it can be read by determining the electrical resistance between the layers.

Conventional MTJs suffer from tiny defects that limit their performance, so researchers are trying to develop more advanced devices based on 2D materials, which may contain only a few atomic layers.

The KAUST team has explored an MTJ design that uses two pieces of the 2D material lanthanum iodide as its ferromagnetic layers. The space between these layers — a van der Waals gap — acts as an insulating barrier. The lanthanum iodide layers are sandwiched between electrodes made from graphene, a honeycomb lattice of carbon atoms. The researchers’ calculations show that switching this MTJ between its two magnetic states — using an external magnetic field — alters the flow of charge between the electrodes.

Read more in KAUST Discovery.