Large Field-like Spin-Orbit Torque and Enhanced Magnetization Switching Efficiency Utilizing Amorphous Mo

Area of Science:

• Materials Science
• Condensed Matter Physics
• Spintronics

Background:

• Spin-orbit torque magnetic random access memory (SOT-MRAM) offers high write speeds and low power consumption.
• Molybdenum (Mo) is explored for its potential to enhance perpendicular magnetic anisotropy (PMA) in CoFeB/MgO-based MRAM cells.
• Despite Mo's potential, its weak spin-orbit coupling makes it a less favored SOT material.

Purpose of the Study:

• To experimentally investigate spin-orbit torque efficiencies in Mo/CoFeB/MgO heterostructures.
• To evaluate the impact of Mo thickness and temperature on SOT properties.
• To demonstrate current-induced magnetization switching using Mo-based heterostructures.

Main Methods:

• Fabrication of Mo/CoFeB/MgO heterostructures.
• Experimental measurement of damping-like (ξDL) and field-like (ξFL) spin-orbit torque efficiencies.
• Temperature-dependent characterization of SOT properties.
• Assessment of current-induced magnetization switching.

Main Results:

• Amorphous Mo exhibits notable SOT efficiencies: |ξDL| = 0.015 ± 0.001 and |ξFL| = 0.050 ± 0.001.
• A high field-like to damping-like SOT efficiency ratio (ξFL/ξDL > 3) was observed.
• Efficient current-induced magnetization switching was achieved with critical current densities comparable to heavy metals like Iridium (Ir) and Tungsten (W).

Conclusions:

• Molybdenum demonstrates significant potential as an SOT source material in SOT-MRAM.
• The findings reveal Mo's viability as a perpendicular magnetic anisotropy (PMA) buffer layer.
• This study opens new avenues for utilizing Mo in advanced SOT-MRAM device applications.