Possible Increase in PC Operating Memory Due to the Unusual Properties of Iodide

At high pressure, chromium iodide crystals start to exhibit remarkable magnetic properties, losing their regular structure and moving into a chaotic, so-called spin-glass arrangement. Their physically exotic behaviour can be used, for example, to increase the capacity of operational memory. Scientists from the J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences and Charles University have found this out. Their study was recently published in the Physical Review B journal.

The speed and performance of computers, mobile phones, and other electronic devices depend on the RAM operational memory. Materials used in current memory devices, such as silicon, have already reached their limits for further reducing the size or speeding up. Therefore, researchers are focusing on two-dimensional (2D) materials whose properties are not yet well examined and may therefore surprise.

Chromium iodide is a 2D material whose crystal structure consists of isolated layers containing chromium and iodine atoms with a thickness of approximately 1 nanometre. An international research team, including scientists from the J. Heyrovsky Institute of Physical Chemistry of the CAS and from Charles University, examined monocrystals of chromium iodide using different pressures and temperatures.

Ferromagnets, antiferromagnets and spin glass

"We subjected the chromium iodide crystal to high pressure, 20 gigapascals or more, and monitored the changes in the magnetic state with a Raman spectrometer," explains Haider Golam from the J. Heyrovsky Institute of Physical Chemistry of the CAS.

"Materials with the spin-glass effect will be used for advanced information storage concepts."

The researchers found out that at a certain pressure and temperature, the crystal behaved very unusually. While at pressures up to 22 gigapascals the 2D material behaved like a ferromagnet, at pressures above 30 gigapascals it behaved like an antiferromagnet. However, in the pressure range of 22 to 30 gigapascals and at low temperature, it began to exhibit exotic properties associated with so-called spin glass.

The possibilities of chaos

Conventional ferromagnetic materials, such as those in magnetic recording media, have magnetic moments (electron spins) oriented in one direction, while in antiferromagnets, their orientation alternates. However, in materials referred to as spin glass, the spins are not arranged regularly, but quite randomly.

"The electron spins in spin glass can take on many different arrangements as they are not periodically arranged as in ordinary magnets. It will be possible to use such magnetic materials for modern information storage concepts," says Jana Kalbáčová Vejpravová from Charles University.

The researchers' study, published last month in the Physical Review B journal, attracted attention and was included in the editor-in-chief´s selection.

"We expect that thanks to the newly discovered properties of 2D magnetic materials, it will be possible to increase the capacity of RAMs and reduce their size," adds Martin Kalbáč of the J. Heyrovsky Institute of Physical Chemistry of the CAS.

Research into 2D materials that exhibit unexpected physical and chemical properties has been a promising research direction only for the past few years. For example, graphene, the first two-dimensional material that has a thickness of one layer of atoms, was discovered just 15 years ago.

Publication: Anirudha Ghosh, et al., Exotic magnetic and electronic properties of layered CrI3 single crystals under high pressure, Physical Review B (2023). DOI: 10.1103/PhysRevB.105.L081104

Original Story Source: Czech Academy of Sciences