New progress in antiferromagnetic spin transport theory

Science and Technology Daily (reporter Wu Changfeng) On June 12, the reporter learned from the Hefei Institute of Physical Sciences of the Chinese Academy of Sciences that Shao Dingfu, a researcher and collaborator of the Institute of Solid State of the Chinese Academy of Sciences, predicted that the spin neutral current in the antiferromagnetic material would carry a special "Nair spin current", and based on this effect, a theoretical scheme of high-performance fully electrically controlled antiferromagnetic tunnel junction was proposed. The relevant research results were recently published in the Physical Review Letters

Science and Technology Daily (reporter Wu Changfeng) On June 12, the reporter learned from the Hefei Institute of Physical Sciences of the Chinese Academy of Sciences that Shao Dingfu, a researcher and collaborator of the Institute of Solid State of the Chinese Academy of Sciences, predicted that the spin neutral current in the antiferromagnetic material would carry a special "Nair spin current", and based on this effect, a theoretical scheme of high-performance fully electrically controlled antiferromagnetic tunnel junction was proposed. The relevant research results were recently published in the Physical Review Letters.

Antiferromagnetic materials have the advantages of zero net magnetic moment, zero stray magnetic field, and ultrafast magnetodynamic response. They are expected to replace ferromagnetic materials and become the next generation Spintronics devices with high density, low power consumption, high stability, and ultrafast read-write. However, it is difficult to control and detect the antiferromagnetic order parameters by conventional methods, which restricts the information reading and writing of antiferromagnetic Spintronics devices. The antiferromagnetic tunnel junction for electrical reading and writing through Tunnel magnetoresistance and spin transfer torque is an ideal device scheme for antiferromagnetic Spintronics. However, because antiferromagnetic materials only have spin degenerate electronic state density, they usually only support spin neutral current, and it is difficult to achieve the Tunnel magnetoresistance effect and spin transfer torque effect for information reading and writing through traditional mechanisms.

On the basis of previous work, researchers further found that if magnetic atoms within the same sublattice in collinear antiferromagnetic materials have strong coupling, they can be approximated as a "parallel circuit" composed of two antiparallel ferromagnetic sublattices. Based on this simple and intuitive physical image, researchers predict that opposite ferromagnetic sublattices in such antiferromagnetic materials will polarize the currents flowing through them, forming two opposing spin currents hidden within the sublattice within the overall spin neutral current. The unique sublattice resolved spin current in this antiferromagnetic material is completely different from the previously well-known macroscopic spin current and is named "Nail spin current".

The "Nair spin current" predicted by this work is a unique transport property of antiferromagnetic materials, which can drive many novel Spintronics effects, such as Tunnel magnetoresistance and spin transfer torque in antiferromagnetic tunnel junctions. The researchers said that this work provides a feasible theoretical framework for high-performance antiferromagnetic tunnel junctions with ultra fast writing and accurate reading, and is expected to promote the development of a new generation of antiferromagnetic Spintronics with the advantages of easy regulation and large switching ratio.

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