Natural crystals fascinate with their vibrant colors, their nearly flawless appearance and their manifold symmetrical forms. But researchers are interested in them for quite different reasons: Among the countless minerals already known, they always discover some materials with unusual magnetic properties.

One of these is atacamite, which exhibits magnetocaloric behavior at low temperatures—that is, the material’s temperature changes significantly when it is subjected to a magnetic field. A team headed by TU Braunschweig and the HZDR has now investigated this rare property. In the long term, the results, now published in Physical Review Letters, could help to develop new materials for energy-efficient magnetic cooling.

The emerald-green mineral atacamite, named for the place it was first found, the Atacama Desert in Chile, gets its characteristic coloring from the copper ions it contains. These ions also determine the material’s magnetic properties: they each have an unpaired electron whose spin gives the ion a magnetic moment —comparable to a tiny needle on a compass.

A condition long considered to be unfavorable to electrical conduction in semiconductor materials may actually be beneficial in 2D semiconductors, according to new findings by UC Santa Barbara researchers published in the journal Physical Review Letters.

Electron-phonon interactions—collisions between charge-carrying electrons and heat-carrying vibrations in the atomic lattice of the material—are considered the primary cause of electrons slowing down as they travel through semiconductor material. But according to UCSB mechanical engineers Bolin Liao and Yujie Quan, when electrons and phonons are considered as a single system, these interactions in atomically thin material prove to actually conserve total momentum and energy, and could have important implications for 2D semiconductor design.

“This is in sharp contrast to three-dimensional systems where you have a lot of momentum loss processes,” said Liao, who specializes in thermal and energy science.

The candidate pool for engineered materials that can help enable tomorrow’s cutting-edge optical technologies—such as lasers, detectors and imaging devices—is much deeper than previously believed.

That’s according to new research from the University of Michigan that examined a class of materials known as topological insulators. These materials have exciting and tunable properties when it comes to how they transmit energy and information.

“We see this as a step toward building a more versatile and powerful foundation for future photonic technologies,” said Xin Xie, a research fellow in the U-M Department of Physics and lead author of the recent study in the journal Physical Review X.