IBM scientists unlock the secret of the Kondo Effect

Mumbai: Scientists at the IBM Almaden Research Centre in San Jose, CA have forged a breakthrough in understanding an intriguing phenomenon in fundamental physics, called the Kondo effect. The report of the findings has been published in the scientific journal Nature Physics.

According to the Kondo effect, many particles collectively behave as one object (a single quantum-mechanical body), which has intrigued scientists around the world for decades. The team of researchers at IBM, using a technique that was developed by the same team in 2007, have shown, for the first time on record, that it is possible to predict when the Kondo effect will occur and also understand why the phenomenon occurs.

When a single magnetic atom is located inside a metal, the free electrons of the metal 'screen' the atom. That way, a cloud of many electrons around the atom becomes magnetised. Sometimes, if the metal is cooled down to very low temperatures, the atomic spin enters a so-called 'quantum superposition' state. In this state its north-pole points in two opposite directions at the same time. As a result, the entire electron cloud around the spin will also be simultaneously magnetised in two directions.

The key in the latest findings turns out to be in the geometry of a magnetic atom's immediate surroundings. By carefully studying how this geometry influences the magnetic moment (or ''spin'') of the atom, the emergence of the Kondo effect can now be predicted and understood. This result represents a major advancement in fundamental physics.
 
The achievement is one of the latest in IBM's more than two decades of nanotechnology leadership and exploration of the world of magnetism at the atomic scale. Starting with the invention of the Scanning Tunneling Microscope (STM) in 1981, IBM has been at the forefront of research aimed at expanding our abilities to investigate and manipulate individual atoms.