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Self-assembling single-digit nanometer memory cells

(Nanowerk News) An international collaborative research team has developed sub-10-nanometer-range spin transfer torque (STT) magnetic tunneling junctions (MTJs).
STT-MRAM (spin-transfer torque-magnetoresistive random access memory) has been intensively researched in recent years and recently been commercialized. The STT-MRAM is capable of replacing existing semiconductor-based working memories due to its excellent capabilities in terms of operation speed and read/write endurance.
Conventional STT-MRAM is based on out-of-plane magnetized MTJs in which the storage layer magnetization is pulled out-of-plane thanks to a perpendicular anisotropy. Design and fabrication of such a device with multi-level signal processing is a major milestone toward future energy-efficient memory and logic operations.
To increase the performance and capacity of STT-MRAM, it has been essential to make the MTJ smaller, while maintaining the capabilities to retain information and be switched by a small current. More recently, several research groups have reported on how to decrease the size of MTJs with good thermal stability by using shape anisotropy of the magnet.
UC Berkeley and Chinese researchers have demonstrated a memory cell to be controllable down to a sub-10-nanometer scale. The STT-MTJ is capable of replacing existing semiconductor-based devices due to its excellent capabilities in terms of power consumption, operating speed, and endurance. Moreover, it is nonvolatile, i.e., no power supply is required to retain stored information, making it indispensable for future ultralow-power electronics.
To further increase the performance and capacity of single-digit-nanometer-range MTJs, it is essential to have a good thermal stability factor of above 65, while maintaining the capabilities to retain information and be switched by very low energy. The demonstrated point contact MTJs shows a thermal stability factor of more than 80.
These research findings, published in the journal Applied Physics Letters ("Self-assembled single-digit nanometer memory cells"), are a major step toward building ultra-low-power STT-MRAM.
"This present work opens a path towards the fabrication of highly energy efficient spin memory devices," concludes Professor Jeongmin Hong from the School of Optical and Electronic Information, Huazhong University of Science and Technology. "Ultimately, we will be able to develop a spin computer the size of a fingernail to replace today's big supercomputer."
Source: Huazhong University of Science and Technology
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