Single-molecule magnet

Molecular nanomagnets, in English, referred to as single- molecule magnets (SMM ) are chemical compounds of metals and organic ligands, which show at very low temperatures at the molecular level, a superparamagnetic behavior.

A molecular nano magnet molecule showing the slow magnetic relaxation. This means that these molecules can be magnetized in a magnetic field and retain this magnetization after removal of the field. These molecules show this purely molecular-based magnetic hysteresis that is not based, in contrast to normal magnets on intermolecular ordering effects. Thus, one material having these properties on a molecular level with other materials, for example plastics, embed and this effect is maintained.

Molecular nanomagnets are complex molecules consisting of a plurality of magnetic metal ions that form organic compounds with the cluster. Were generated molecules having up to 82 metal ions, the typical size is 30 to six active magnetic atoms. Typical metals involved are chromium, iron, manganese, nickel and copper.

The typical configuration is, that is, such as O2, OH -, Cl - linked by simple bonds the magnetically active paramagnetic metal ions of such a molecule in the interior and are shielded to the outside by the organic ligands of the environment.

The class is interesting because it is real nanomaterials with a size of several nanometers and effects such as Magnetism, on the one hand strictly quantum mechanically, on the other hand, behave according to the laws of classical physics. That is, these molecules move at the interface of these two areas of physics.

Blocking temperature

The measurements take place at very low temperatures. It is interesting in this context the so-called blocking temperature, below this, the effect of the relaxation is slow compared to the method of investigation. For example, a molecule that has been magnetized at 2 K, after 60 days still 40% of the magnetization. The temperature is lowered to 1.5 K, the same value would be achieved after 40 years.

History

The research on these substances are a part of the field of nanoscience. The underlying effect of the magnetic relaxation is slow since 1933, was first observed when the effect on the Mn12 examined. The term "single- molecule magnet" was coined by David Hendrickson, a chemist at the University of California, San Diego, and George Christou (Indiana University) in 1996. The first reports date back to the year 1991 by European explorers as they effect on Mn12O12 ( MeCO2 ) 16 ( H2O) 4 complex ( Mn12Ac16 ), which was synthesized in 1980 for the first time observed.

Applications

Potential applications are envisaged in the field of quantum computing and the nanoscopic store. In the area of ​​storage technologies, these materials are very interesting, as you can imagine such a molecule than one bit and thus extremely high data densities would be feasible. It would be data densities of up to 100 Tbit/in2 (150 Gbit / mm ² ) can be achieved, which is three to four orders of magnitude above the currently possible.