Magnetic Random Access Memories (MRAM) is a non-volatile memory technology, where information is stored by the magnetization direction of magnetic electrodes, very similar to computer hard-disk drives. The goal for MRAM memory is to simultaneously achieve high-speed read/write times, high density and unlimited cycling compared to other existing and emerging technologies.
Our group is developing advanced MRAM cell concepts patented at Spintec. The concepts are based on the use of temperature to reduce power consumption and increase the stability of the stored information. These ideas go beyond the conventional MRAM approach. The naturally occurring temperature increase during the write step is not lost, but is instead used to achieve the seemingly opposing goal of lowering the power consumption and increasing the thermal stability in the operating temperature range. Our group fosters young and experienced researchers developing/applying their expertise in the field of MRAM.
Questions to be addressed
Our main research axis is to use the naturally occurring temperature increase during the write step, when a current flows through the magnetic tunnel junction. The heating is used to go above a temperature threshold, making it possible to write the storage layer magnetization. This principle has been applied to in-plane magnetization cells using a storage layer pinned by an anti-ferromagnet and recently to perpendicular anisotropy cells. Our group’s goal is to demonstrate the proof-of-concept and then improve MRAM cell properties.
Our work involves the development of magnetic material systems, nano-fabrication (20-200nm cells), characterization of devices (magnetic & electrical) and simulation of the device behavior. Our activity in these vast fields is as follows;: On materials research, we are developing magnetic tunnel junctions with in-plane and perpendicular magnetic anisotropy. New electrode stacks having the material properties required by each specific concept need to be integrated in magnetic tunnel junctions, while achieving high levels of TMR signal. For the characterization of each concept we determine the write window parameters in terms of magnetic field, power consumption and magnetization reversal dynamics. Macrospin and micromagnetic simulation provide a better physical understanding of the system properties and the possibilities for optimization.
ANR EXCALYB – Perpendicular Anisotropy Materials for High-Density Non-volatile Magnetic Memory Cells
Crocus R&D – Thermally assisted MRAM
- WP5 : FABRICATION AND TEST OF HYBRID CMOS/MTJ CIRCUITS [July 02nd, 2015]
For the fabrication of CMOS/MTJ circuits, three different technological lines were developed and made accessible for HYMAGINE purposes. For simple circuits comprising only a few MTJs interconnected with CMOS transistors, the PTA 400m² upstream research clean-room ...
- WP4 : DESIGN OF LOW-POWER HYBRID CMOS/MAGNETIC CIRCUITS [July 02nd, 2015]
Within HYMAGINE, circuits of increasing complexity have been conceived from simple non-volatile logic gates to microcontrollers or microprocessor. Below is an example of magnetic Look-Up-Table (MLUT) conceived within HYMAGINE and an example of hybrid CMOS/MTJmicroprocessor. Magnetic LUT ...
- WP2 : SWITCHING SPEED AND COHERENCE [July 02nd, 2015]
Thanks to their unique set of assets (non-volatility, speed, density, endurance), STT-MRAM are seen as a unique candidate for DRAM and/or Cache SRAM replacement allowing to drastically reduce the power consumption of electronic circuits thanks ...
- WP3 : MODELLING AND DESIGN TOOLS [July 02nd, 2015]
Modelling and design tools were developed in the frame of HYMAGINE to cover both the fundamental and design aspects of the project. Concerning the fundamental aspects, we developed a code allowing to calculate both the transport ...
- MAGNETOSTATICS OF SYNTHETIC FERRIMAGNET ELEMENTS [July 02nd, 2015]
Olivier Fruchart,-, Bernard Diény We calculate the magnetostatic energy of synthetic ferrimagnet (SyF) elements, consisting of two thin ferromagnetic layers coupled antiferromagnetically, e.g. through RKKY coupling. Uniform magnetization is assumed in each layer. Exact formulas as ...