Ferrimagnetic Heusler tunnel junctions with fast spin-transfer torque switching enabled by low magnetization

Area of Science:

• Materials Science
• Condensed Matter Physics
• Electrical Engineering

Background:

• Magnetic random-access memory (MRAM) offers high performance and non-volatility, surpassing traditional charge-based memory.
• Current MRAM speed is constrained by the high magnetization of its memory storage layer.
• Overcoming this limitation is crucial for advancing memory technology beyond current nodes.

Purpose of the Study:

• To engineer magnetic tunnel junction (MTJ) memory devices with a low-magnetization storage layer.
• To investigate the feasibility of using ferrimagnetic Heusler alloys for next-generation MRAM.
• To demonstrate reliable switching and magnetoresistance in MTJ devices with novel materials.

Main Methods:

• Fabrication of MTJ memory devices utilizing a low magnetization ferrimagnetic Heusler alloy (Mn3Ge) as the storage layer.
• Implementation of a nitride seed layer and a chemical templating layer on amorphous substrates.
• Characterization of magnetic state switching using nanosecond write pulses and measurement of tunneling magnetoresistance (TMR).

Main Results:

• Successful fabrication of MTJ memory devices with Mn3Ge storage layers on amorphous substrates.
• Achieved reliable magnetic state switching with a write error rate of 10^-7 using nanosecond pulses.
• Detected a significant tunneling magnetoresistance (TMR) of 87% at ambient temperature.

Conclusions:

• The use of low-magnetization ferrimagnetic Heusler materials like Mn3Ge presents a viable strategy for MRAM.
• This approach facilitates lower write switching currents, paving the way for MRAM scaling.
• The developed MTJ devices demonstrate potential for high-performance, non-volatile memory beyond current ferromagnetic limitations.