Untapped potential of a promising technology

A look at the features, applications and operation of MRAM technology

MRAM (Magnetoresistive RAM, Racetrack Memory)

MRAM (Magnetoresistive RAM) is a type of non-volatile RAM (Random Access Memory). This means that the data is retained for a while, even if the power supply is interrupted. Unlike most other types and subtypes of RAM (such as the DRAM, the SRAM or even the FRAM), the MRAM stores information not with electrical but with magnetic charge elements: based on the parallel or antiparallel alignment of two ferromagnetic plates.

Features of the FeRAM
Areas of application for FeRAM
Functionality of the FeRAM
Sources

Features of the MRAM

MRAM technology offers several advantages, including high speed, long life, and the ability to store data without power. However, there are still several challenges to overcome before it can be deployed on a large scale, including the difficulty of shrinking MRAM cells to increase storage density.

Here is a summary of the main features of the storage technology:

MRAM offers excellent data retention, with the ability to store data over long periods. This makes it ideal for applications where data must be preserved even in the event of a power outage.

Unlike flash memory, which needs a separate erase phase before new data can be written, MRAM allows for faster writing operations. This high speed results from the immediate change of the magnetic states used to store information.

MRAM can achieve an extremely high number of write and erase cycles (up to 1015 or more) compared to flash memory or EEPROM (typically 103 to 106). This makes it ideal for applications that require frequent write operations.

MRAM consumes less power than many other memory technologies, especially during writing operations. This makes it ideal for energy-efficient applications.

MRAM uses magnetoresistive materials for its memory cells. These materials change their magnetic orientation to store information, and maintain their state even when the power supply is switched off.

Beware of confusion!

Ferromagnetic (MRAM) vs. Ferroelectric (FRAM)

The term "ferro" comes from Latin and means iron (ferrum). Both "ferromagnetic" and "ferroelectric" refer to properties that were originally discovered in materials containing iron, although the terms now apply to a wider range of materials.

Ferromagnetic: Iron (Fe) is a well-known example of a ferromagnetic material. Ferromagnetic materials can have a permanent magnetic field when they are exposed to an external magnetic field. This phenomenon is the basis for the operation of MRAM.

Ferroelectric: The term "ferroelectric" was chosen because of its similarity to the phenomenon of ferromagnetism, despite the fact that iron itself is not ferroelectric. Ferroelectric materials can have a permanent electrical polarization that can be changed by an external electric field. This is the basis for the operation of FRAM.

MRAM is very resistant to radiation, making it a good choice for applications in space and in radiation-intensive environments.

MRAM can be operated over a wide range of temperatures, making it versatile.

Despite the many advantages of MRAM, there are still significant obstacles to its widespread market introduction. The difficulties in miniaturizing MRAM cells to increase storage density and the higher costs compared to established technologies such as DRAM and flash are particularly problematic.

Despite decades of development work, FRAM and MRAM semiconductor memories are now producible and available, but their storage density is significantly behind that of current SDRAM semiconductor memories. For this reason, FRAM and MRAM are currently not considered as replacements for flash or SDRAM memory.

Applications for MRAM

A quick note: Whether the use of MRAM is recommended for certain applications cannot be said in general terms and always depends on a variety of application-specific factors. With the following information on the suitability of MRAM for various applications, we do not want to make any purchase recommendations, but rather put the properties of MRAM memory technology into context.

Like FeRAM, MRAM is well suited for industrial control systems as it can quickly and reliably store data, even in the event of sudden power outages or other disturbances.

Due to its high resistance to physical and electrical stress, MRAM is well suited for automotive applications, including safety systems and infotainment components.

In network equipment, MRAM can be used to quickly store and retrieve data, which can improve the performance and efficiency of the systems.

Operation of the MRAM

MRAM stores data using magnetic states rather than electric charges (like DRAM, for example). In the smallest storage unit (cell) of an MRAM, there are two ferromagnetic plates separated by a thin insulating film. One of the plates has a fixed magnetic state (fixed layer), while the other (free layer) can change its magnetic state.

Data is represented in an MRAM cell by the relative magnetic orientation of the two plates. If the magnetic orientation of the two plates is parallel (both pointing in the same direction), this is interpreted as "0". If the orientations are antiparallel (they point in opposite directions), this is interpreted as "1". The data is read by sending a small current through the cell. Depending on the orientation of the magnetic fields of the two plates, the electrical resistance of the cell will vary. This difference in electrical resistance can then be detected and interpreted as bit "0" or "1".

Writing data to an MRAM cell requires more energy. A stronger current is sent through the cell to reverse the magnetic field of the changeable plate and thus change the magnetic orientation.