Long Room (EUA)

Researchers achieve almost instant magnetization of matter by light

Publicado em 28 maio 2018

The production of devices to store or transmit information is one of the most frequent technological applications of magnetism. An experimental and theoretical study conducted at the University of São Paulo's Physics Institute (IF-USP) in Brazil has discovered an ultrafast way of magnetizing matter with minimal energy consumption.

Using a technique called magnetization by light, the researchers magnetized a sample of europium selenide (EuSe) in 50 picoseconds with a 50-watt bulb located a few centimeters away. A picosecond is one trillionth of a second.

Article - Experiment - Ultrafast - Switching - Ferromagnetism An article describing the experiment, titled "Ultrafast light switching of ferromagnetism in EuSe," was recently published in Physical Review Letters.

The experiment was conducted by André Bohomoletz Henriques, a full professor at IF-USP, and collaborators with support from the São Paulo Research Foundation—FAPESP.

Aim - Mechanisms - Magnetism - Materials - Time "Our aim was to find new mechanisms to change the magnetism of materials in an ultrashort time scale using only light. The novelty of our research is that it makes very strong magnetization possible with very small amounts of light," Henriques said.

The process was experimentally derived at the University of São Paulo's Magneto-Optics Laboratory, but interpreting the phenomenon required substantial theoretical work, involving procedures such as self-consistent quantum mechanical calculations and Monte Carlo simulations, on the part of the group led by Henriques.

Magnetization - Material - Ordering - Spins - Constituent The magnetization of a material is associated with the spatial ordering of the spins of its constituent particles. In an unmagnetized material, the spins of its atoms (resulting from the spins of its electrons) are disordered. Because vector magnitude is involved, the spin of each atom points in an arbitrary direction. In certain situations, these spins can be ordered by light, which, as a result, can completely magnetize an initially disordered material. The image above illustrates the process of magnetization by light.