Improving memory

Nat. Commun. 8, 13985 (2017)

The ferromagnetic materials used for the fabrication of magnetic random access memory devices are sensitive to spurious magnetic fields, usually causing undesired instabilities. Furthermore, the need for charge currents to encode information increases the overall power consumption of these devices. Several approaches reported in the literature have addressed these issues separately by using either antiferromagnetic materials — aiming at better device stability — or magnetoelectric materials, enabling writing processes via electric fields, hence without any power dissipation due to electric currents.

Now, Kosub et al. report on the use of these approaches simultaneously, describing a random access memory prototype that works at room temperature and is based on α-Cr₂O₃ — a magnetoelectric antiferromagnet. An ultrathin layer of Pt, which has a high paramagnetic polarizability, makes it possible to sense the magnetic state of α-Cr₂O₃. This precaution avoids coupling Cr₂O₃ to ferromagnetic materials and allows the researchers to perform all-electrical read-out processes via anomalous Hall magnetometry. A thicker Pt electrode allows data writing in combination with a static magnetic field that need not be removed during the read-out stage.

Energy is consumed only during the write and read stages. Also, the reported writing thresholds are sizably lowered if compared to the devices based on ferromagnets.