Inverse magnetoelectric effects at the nanoscale for MRAM applications

Magnetic memories are presently intensely researched for embedded memory applications. Especially magnetic random-access memory (MRAM) has recently been started to be commercialized in consumer appliances and it can be expected that it will become broadly used in the near future. In such magnetic memories, the information is stored in the orientation of the perpendicular magnetization in a magnetic tunnel junction. The resistance of the tunnel junction is used to read the information whereas spin-transfer torque is used to write the information. To improve the performance of the cell and to open new application fields, both the read and write speed of the MRAM cells need to be improved without affecting the memory retention.

To date, much research is being devoted to improving the write performance of MRAM cells using e.g. spin-orbit torques or voltage-controlled magnetic anisotropies. By contrast, rather little attention has been paid to the read performance of MRAM cells. To improve the read performance, voltage-based schemes using magnetoelectric materials and compounds appear promising. In recent years, magnetoelectricity has seen a renaissance due to technological and theoretical progress and its research has focused on manipulating magnets by electric fields for both memory and logic applications. In such applications, magnetoelectricity promises much higher power efficiency than conventional charge-spin conversion by spin-transfer or spin-orbit torques. Concerning the opposite challenge of spin-charge conversion, little attention has been devoted to inverse magnetoelectric effects as read mechanism in memory devices so far.