Two-dimentional (2D) van der Waals (vdW) materials possess diverse electronic properties, providing new opportunities for building high-preformance electronic devices. Studies on 2D vdW materials have mainly focused on the non-magnetic ones. However, the presence of magnetic anisotropy gives arises to the recent observations of intrinsic magnetism in 2D vdW materials.

Magnetic 2D vdW material provides a versatile platform for developing novel spintric devices. The large family of vdW materials and numerous combinations of vdW heterostructures remarkably extend the material choices and can be visioned as new building blocks for electronic and spintronic applications in the near future.

In order to utilize 2D vdW ferromagnets for building spintronic nano-devices such as magnetic memories, key challenges remain in terms of effectively switching the magnetization from one state to the other electrically.

A joint research team from the Chinese Academy of Sciences (CAS) made progress in electrically controlling the magnetization of vdW magnets. They developed a convenient method combining the ferromagnetism of vdW materials with the spin Hall Effect of an adjacent heavy metal layer. Their study was published in Science Advances on August 24.

The team includes Prof. HAN Xiufeng's group and Prof. ZHANG Guangyu's group from the Institute of Physics, and Prof. HAN Zheng's group from the Institute of Metal Research.

When an electrical current flowed in the heavy metal, a spin current was generated and injected into the vdW magnet. The spin current then transferred angular momentum to the magnetic moment and induced a magnetization switching.

Based on this scheme, the researchers devised a bilayer structure of Fe₃GeTe₂/Pt, in which the magnetization of few-layered vdW magnet Fe₃GeTe₂ (FGT) could be effectively controlled by the spin current originated from the electrical current flowing in the Pt layer.

The magnetization of FGT could be switched from one state to the other by applying electric currents. Two distinct states could be well sustained at zero current, which was monitored by a positive or negative Hall voltage.

These two distinct magnetic states and the corresponding output voltages can be encoded as "0" and "1" states in the magnetic memory application. This proof-of-concept spintronics device highlights the potential of magnetic vdW materials and their compatibilities with spintronic technologies.

Regarding the reported devices, there are still challenges for practical applications, such as room-temeprature 2D magnetism, low-density switching current, fabrication of wafer-scale 2D magnetic vdW materials, and the integration with present semcondictor technique. However, the study on 2D magnetic vdW materaisls just rises up. Their fast developments will further advance the performance of ultra-compact spintronics devices for practical applications.

The study was supported by the National Key Research and Development Program of China, the National Science Foundation, the NSFC-Science Foundation Ireland (SFI) Partnership Programme, the Strategic Priority Research Program (B) of CAS, the Key Research Program of Frontier Sciences of CAS, and the National Key R&D program of China.

Schematic view and characterizations of FGT/Pt bilayer. (Image by IOP)