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Jing Shi is a professor in the Department of Physics and Astronomy at UC Riverside. Credit: I. Pittalwala, UC Riverside.
A team of physicists has discovered an electrical detection method for terahertz electromagnetic waves, which are extremely difficult to detect. The discovery could help miniaturize the detection equipment on microchips and enhance sensitivity.
Terahertz - Unit - Wave - Frequency - Gigahertz
Terahertz is a unit of electromagnetic wave frequency: One gigahertz equals 1 billion hertz; 1 terahertz equals 1,000 gigahertz. The higher the frequency, the faster the transmission of information. Cell phones, for example, operate at a few gigahertz.
The finding, reported today in Nature, is based on a magnetic resonance phenomenon in anti-ferromagnetic materials. Such materials, also called antiferromagnets, offer unique advantages for ultrafast and spin-based nanoscale device applications.
Researchers - Physicist - Jing - Shi - University
The researchers, led by physicist Jing Shi of the University of California, Riverside, generated a spin current, an important physical quantity in spintronics, in an antiferromagnet and were able to detect it electrically. To accomplish this feat, they used terahertz radiation to pump up magnetic resonance in chromia to facilitate its detection.
In ferromagnets, such as a bar magnet, electron spins point in the same direction, up or down, thus providing collective strength to the materials. In antiferromagnets, the atomic arrangement is such that the electron spins cancel each other out, with half of the spins pointing in the opposite direction of the other half, either up or down.
Electron - Spin - Momentum - Way - Precesses
The electron has a built-in spin angular momentum, which can precess the way a spinning top precesses around a vertical axis. When the precession frequency of electrons matches the frequency of electromagnetic waves generated by an external source acting on the electrons, magnetic resonance occurs and is manifested in the form of a greatly enhanced signal that is easier to detect.
In order to generate such magnetic resonance, the team of physicists from UC Riverside and...
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