Terahertz Light has the ability to control solid matter at the atomic level, forming left-handed and right-handed chiral structures. Credit: Zhiyang Zeng (MPSD)
Chirality refers to objects that cannot be superimposed into mirror images through any combination of rotation or translation, such as a person’s distinct left and right hands. In chiral crystals, the spatial arrangement of the atoms introduces a certain “handedness.” For example, it sheds optical properties and electrical properties.
The Hamburg-Oxford team focuses on so-called anti-ferrochirals. It focuses on a type of non-chiral crystal reminiscent of anti-Phallo magnetic materials, where the magnetic moments are anti-aligned in a staggered pattern that leads to the disappearance of net magnetization. Antiferrochiral crystals consist of equal amounts of left- and right-handed substructures within the unit cell, making them globally achiral.
A research team led by Andrea Cavalleri at the Max-Planck-Institut for the Structure and Dynamics of Matter uses Terahertz light to lift this balance in the non-chiral material boron phosphate (BPO4), thus Inducing finite chirality and ultra-fast timescales.
The team’s research is published in the journal Science.
“We exploit a mechanism called nonlinear phononics,” says Zhiyang Zeng, lead author of the work. “By stimulating a specific terahertz frequency vibrational mode that displaces the crystal lattice along the coordinates of other modes in the material, we created a chiral state that survives for a few picoseconds,” he added.
“In particular, by rotating the polarization of the terahertz light by 90 degrees, we can selectively induce left- or right-handed chiral structures,” continues author Michael Ferst.
“This discovery opens new possibilities for the dynamic control of materials at the atomic level,” said Cavalleri, group leader at MPSD. “We look forward to seeing the potential applications of this technology and how it can be used to create unique functionality. The ability to induce chirality in non-chiral materials could be used in ultrafast memory devices or even more sophisticated This could lead to new applications for optoelectronic platforms.
Details: Z. Zeng et al, Photo-induced chirality in non-chiral crystals, Science (2025). doi:10.1126/science.adr4713
Provided by the Max Planck Institute for the Structure and Dynamics of Matter
Citation: Terahertz pulses are non-chiral crystals recovered on January 23, 2025 from https://phys.org/2025-01-terahertz-pulses-chirality-chiral-crystal.htmll (January 23, 2025) to induce chirality.
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