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Materials Chemistry

Nanosized Memory

In the world of technology where downsizing is essential, a development led by CNRS researchers promises further advances down the path of miniaturization. The innovation is in the field of molecular nanomagnets–tiny magnets capable of storing binary information due to their magnetic bistability, i.e., the ability to pass from one state to another (on and off) in response to an external stimulus.
Until now, bistability had only been found in condensed molecular clusters, since isolated molecules tend to lose this trait. However, a team1 led by Talal Mallah, from ICMMO2 and the Institut Lavoisier3 has now managed to isolate a single-molecule magnet (SMM) that keeps its memory storage capacity.4
nanosized memory

© T. Mallah/ICMMO

Isolated single-molecule magnet of Fe6-polyoxometalate (High resolution Transmission Electron Microscope image) assembled on carbon nanotubes.

The team's winning strategy is to graft an SMM of Fe6-polyoxometalate5 onto a single-wall carbon nanotube, retaining not only its chemical integrity but also its magnetic bistability. Currently being used to develop a device called nanoSQUID (Superconducting Quantum Interference Device) for measuring the magnetism of tiny objects, the advance also paves the way for what Mallah calls “information storage systems with remarkably high density.”
Information can be stored by SMMs in ultra-compact electronic devices only if scientists find a way to manipulate their magnetism. And as results indicate that the carbon nanotube's electronic properties help the SMM switch magnetic states, future devices can potentially capitalize on this synergy.
The team further shows that the carbon nanotube and polyoxometalate mix speeds up electron travel between electrode and molecule, causing “a significant energy gain,” according to Mallah. This discovery opens up prospects for the hybrid system as a “high-performance electrode” in electrocatalytic procedures for energy conversion or hydrogen production.
Taking its tests beyond polyoxometalates, the team is now exploring the possibility of grafting other types of single magnetic molecules, as well as single photoactive ones that respond to light.

Fui Lee Luk

Notes :

1. Laboratoire de Chimie Physique (CNRS / Université Paris-11), Laboratoire d'Électronique Moléculaire (CEA-Saclay), and the Institut Néel (CNRS).
2. Institut de Chimie Moléculaire et des Matériaux d'Orsay (CNRS / Université Paris-11).
3. CNRS / Université de Versailles Saint-Quentin.
4. A. Giusti et al., “Magnetic Bistability of Individual Single-Molecule Magnets Grafted on Single-Wall Carbon Nanotubes,” Angew. Chem., 2009. 121: 5049-52.
5. A polyoxometalate is a polyatomic ion where transition metal compounds are linked by oxygen atoms.

Contacts :

Talal Mallah,
ICMMO, Orsay.


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