Novel two-dimensional homogeneous bias device

In a research published in advanced content recentResearchers from the Hefei Institute of Physical Science (HFIPS) of the Chinese Academy of Sciences describe how they developed a new type of two-dimensional homogeneous bias device with moderate pressure in collaboration with researchers from the University of Science and Technology of China.

Compared to three-dimensional similar devices, the two-dimensional bias device was described as “non-aging, extensible and recoverable”.

“It provides a new idea for the design of low-dimensional magnetic devices and the study of the exchange bias effect mechanism,” said Sheng Zhigao of HFIPS, “and we expect it to become the main magnetic component in two-dimensional electronic technology and equipment.”

Two-dimensional van der Waals magnetic materials provide an excellent platform for basic magnetic research and low-dimensional magnetic device development because of their layered structure, no dangling bonding surface and strong magnetic anisotropy. However, the weak interlayer coupling greatly limits the functional device application of two-dimensional magnetic materials. Therefore, how to effectively achieve strong magnetic exchange through interface engineering has become one of the key issues in the fabrication of two-dimensional magnetic devices.

In this research, the research team used a variety of materials and technical methods. They found that the two-dimensional iron germanium tellurium (Fe₃gete₂) materials with a ferromagnetic ground state can be induced into a homogeneous and magnetic heterostructure with ferromagnetic-antiferromagnetic coexistence by uniaxial pressure technology.

Also, they found that there is a practical exchange bias effect of the structure.

This pressure-induced phase transition was confirmed by magneto-optical testing, high-resolution transmission electron microscopy and first-principle calculations.

Since the ferromagnetic–antiferromagnetic coupling of the material’s homogeneous and magnetic heterostructure occurs inside the homogeneous junction, its exchange bias effect exhibited excellent characteristics for an atomically smooth magnetic interface.

“These features (non-aging, expandable and rechargeable) cannot be found in three-dimensional devices,” said team member Hou De.

This result paved a new way for the design and development of high-performance two-dimensional magnetic devices, and its excellent exchange bias characteristics provided an opportunity for effective application of two-dimensional magnetic devices.