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Scientists discover a 2-D magnet

Magnetic materials form the basis of technologies that play increasingly pivotal roles in our lives today, including sensing and hard-disk data storage. But as our innovative dreams conjure wishes for ever-smaller and faster devices, researchers are seeking new magnetic materials that are more compact, more efficient and can be controlled using precise, reliable methods.

A team led by the University of Washington and the Massachusetts Institute of Technology has for the first time discovered magnetism in the 2-D world of monolayers, or materials that are formed by a single atomic layer. The findings, published June 8 in the journal Nature, demonstrate that magnetic properties can exist even in the 2-D realm – opening a world of potential applications.

“What we have discovered here is an isolated 2-D material with intrinsic magnetism, and the magnetism in the system is highly robust,” said Xiaodong Xu, a UW professor of physics and of materials science and engineering, and member of the UW’s Clean Energy Institute. “We envision that new information technologies may emerge based on these new 2-D magnets.”

Xu and MIT physics professor Pablo Jarillo-Herrero led the international team of scientists who proved that the material – chromium triiodide, or CrI3 – has magnetic properties in its monolayer form.

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Physicists resolve long-standing mystery of structure-less transition

We normally associate conduction of electricity with metals. However, some of the high measured conductivities are found in certain organic molecular crystals. Metallic, semiconducting and even superconducting properties can be achieved in these materials, which have interested scientists for decades. Changing temperature or pressure causes phase transitions in the crystal structure of molecular conductors and their related conduction properties. Scientists can usually determine the crystal structure using X-ray diffraction. However, structural change accompanying phase transition in a particular organic crystal (TMTTF)2PF6 has defied examination for almost 40 years.

Now, a research team at Nagoya University has finally explained the mysterious structural changes of this phase transition and its related electronic behavior.

“Researchers have questioned that the TMTTF (tetramethyltetrathiafulvalene) salt shows a charge disproportionation transition at 67 Kelvin but no relevant changes in its crystal structure. This transition is a long-standing mystery known as a ‘structure-less transition’,” explains lead author Shunsuke Kitou.

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