Rise of the Underdog: A Neglected Mechanism in Antiferromagnets May be Key to Spintronics
upstart writes in with an IRC submission:
Rise of the underdog: A neglected mechanism in antiferromagnets may be key to spintronics:
Enormous efforts are being made worldwide in a technological field that could far surpass the capabilities of conventional electronics: spintronics. Instead of operating based on the collective movement of charged particles (electrons), spintronic devices could perform memory storage and data transmission by manipulating spin, an intrinsic property of elementary particles related to angular momentum and from which many magnetic characteristics in materials arise. Unfortunately, controlling spin has proven to be a challenging endeavor, leading physicists and engineers to look for efficient materials and techniques to do so.
In this regard, antiferromagnetic materials (AFMs) are good candidates for spintronics because they are resistant to external magnetic fields and allow for switching spin values in timescales of picoseconds. One promising strategy to manipulate spin orientation in AFMs is using an optical laser to create extremely short-lived magnetic field pulses, a phenomenon known as the inverse Faraday effect (IFE). Although the IFE in AFMs generates two very distinct types of torque (rotational force) on their magnetization, it now seems the most important of the two has somehow been neglected in research.
In a recent study published in Nature Communications, a trio of scientists, including Professor Takuya Satoh from the Tokyo Tech, Japan, delved deep into this issue. Spin dynamics in AFMs are described by a sum of two terms: field-like torque and damping-like torque. The latter, as the word 'damping' implies, is related to the gradual decay (or dying off) of the spin oscillations triggered by the optical pulses on the material.
[...] Although much more research will certainly be needed before applied spintronics becomes a reality, uncovering efficient mechanisms for spin manipulation is obviously among the first steps. This study proves that such mechanisms might be hidden in phenomena we know and neglect!
Journal Reference:
Christian Tzschaschel, Takuya Satoh, Manfred Fiebig. Efficient spin excitation via ultrafast damping-like torques in antiferromagnets [open], Nature Communications (DOI: 10.1038/s41467-020-19749-y)
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