Highly Energy-Efficient Spin-Orbit-Torque Magnetoresistive Memory with Amorphous W―Ta―B Alloys

The spin Hall effect enables fast and reliable writing operations for next-generation spin-orbit-torque magnetoresistive random-access memories (SOT-MRAMs). To develop SOT-MRAMs; however, the spin Hall material should have a sufficiently low writing energy and high annealing stability for the semiconductor integration process. Thus far, none of the crystalline-based spin Hall materials are able to satisfy these requirements. Here, a promising solution for SOT-MRAMs is provided using amorphous WTaB alloys. Even without a long-range crystal order, WTaB alloys exhibit both large effective spin Hall angles up to 40% derived from a Ta substitutional doping and superior annealing stability (up to 400 degrees C) due to the addition of B, enabling them to satisfy both requirements. Nanoscale three-terminal SOT-MRAM cells are fabricated, and these are demonstrated to have high magnetoresistance ratios (up to 130%) and extremely low intrinsic switching current densities (down to 4 x 106 A cm-2). These results show that amorphous spin Hall materials can provide the key for realizing high-performance SOT-MRAMs. The successfully synthesized amorphous WTaB alloys as a solution for developing ultimate high-performance non-volatile memory, spin-orbit-torque magnetoresistive random access memory (SOT-MRAM). The amorphous alloys exhibit unexpected high performances such as large spin Hall effect (up to 40%) and excellent thermal annealing stability (up to 400 degrees C), satisfying all the major requirements for high-performance SOT-MRAM.image

Automated summary

This study presents a solution for developing high-performance SOT-MRAM by using amorphous WTaB alloys as spin Hall materials. The amorphous alloys exhibit high spin Hall effect and excellent thermal annealing stability, meeting the requirements of SOT-MRAM.