Ultrafast Terahertz Magnetometry: New Method to Track Ultrafast Change of Magnetic State

Ultrafast Terahertz Magnetometry: New Method to Track Ultrafast Change of Magnetic State

An international team of physicists from Bielefeld University, Uppsala University, the University of Strasbourg, University of Shanghai for Science and Technology, Max Planck Institute for Polymer Research, ETH Zurich, and the Free University Berlin have developed a precise method to measure the ultrafast change of a magnetic state in materials. They do this by observing the emission of terahertz radiation that necessarily accompanies such a magnetization change. Their study, titled ‘Ultrafast terahertz magnetometry,’ is being published recently in Nature Communications. Magnetic memories are not just acquiring higher and higher capacity by shrinking the size of magnetic bits, they are also getting faster. In principle, the magnetic bit can be ‘flipped’—that is, it can change its state from ‘one’ to ‘zero’ or vice versa—on an extremely fast timescale of shorter than one picosecond. One picosecond (1 ps = 10-12 s) is one millionth of one millionth of a second. This could allow the operation of magnetic memories at terahertz (1 THz = 1 x 1012 hertz) switching frequencies, corresponding to extremely high terabit per second (Tbit/s) data rates. ‘The actual challenge is to be able to detect such a magnetization change quickly and sensitively enough,’ explains Dr. Dmitry Turchinovich, professor of physics at Bielefeld University and the leader of this study. ‘The existing methods of ultrafast magnetometry all suffer from certain significant drawbacks such as, for example, operation only under ultrahigh vacuum conditions, the inability to measure on encapsulated materials, and so on. Our idea was to use the basic principle of electrodynamics. This states ...
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