Predicting the Kondo Effect

Scientists at the IBM Almaden Research Center have discovered a major advancement in fundamental physics. For the first time ever, researchers are able to predict when the Kondo effect will occur.

The Kondo effect is one of the few examples in physics where many particles collectively behave as one object, or a single quantum-mechanical body.

Essentially, the Kondo effect occurs when electrons become trapped around the magnetic impurities in semiconductor materials, which prompts the electrons to change their spin.

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 magnetized in two directions.

This phenomenon is being studied using a technique that was developed by the same team in 2007. The key 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, which has intrigued scientists around the world for decades, is one of the latest in IBM’s more than twenty years of nanotechnology 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.

For more information, visit: www.ibm.com

(See also: Double Qdots Control Kondo Effect)