Inverse magnetoelectric effects 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. In such magnetic memories, the information is stored in the orientation of the perpendicular magnetization in a magnetic tunnel junction. 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; by contrast, rather little attention has been paid to the read performance.

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.

Within this thesis, the student will study the inverse magnetoelectric effects to generate voltage signals based on the magnetization of a nanomagnet. The work will concentrate on innovative materials and emphasis will be on the fundamental understanding of the magnetoelectric coupling at the nanoscale. To this aim, the student will fabricate and measure test devices to quantify the coupling and deduce its relation to materials properties. The results will allow for an evaluation of the prospects of inverse magnetoelectricity for disruptive read mechanisms and pave the way for applications in future magnetic memories. The experimental work will be supported by modeling activities (materials, devices, circuits) in the spintronics group at imec. The student should have a strong interest in nanofabrication in a cleanroom environment as well as in leading edge research topics on magnetism and magnetic materials.​