A team of Princeton scientists has observed Majorana fermions, legendary antimatter particles named after Italian physicist Ettore Majorana. In 1937, Majorana suggested that some particles might in fact serve as their own antimatter particles, and this is exactly what the researchers observed when they placed a magnetic iron atom chain system close to a conventional lead superconductor.

The research, reported online on October 2 in the journal Science Magazine, shows that what was up to then only theoretical is a case where the suatomic particles are capable of existing as both matter and antimatter at the same time.
The scientists, led by Ali Yazdani of Princeton University, observed the Majorana particles on a superconductor in which electrons can move completely unimpeded and electricity can flow with no resistance. Superconductivity, which also exhibits the expulsion of magnetic fields, occurs in certain metals when they are cooled below a critical temperature characteristic to each material.

Magnetic fields disrupt superconductors, but in this experiment, the researchers placed ferromagnetic atom chains on top of the lead superconductor. The magnetic atom chain resulted in a superconductor in which electrons in the chain adjacent to one another exhibited coordinated spins, satisfying the requirements of magnetism and superconductivity simultaneously.

As the researchers explain, the pairs of adjacent electrons with coordinated spins are in effect made of one electron and one antielectron, one with a negative charge and one with a positive charge. One electron at each end of the ferromagnetic chain does not have a partner with which to pair. As a result, these end electrons assume the properties of both electrons and antielectrons, which satisfies the criteria of the Majorana particle.

“The great thing about Majoranas is that they are potentially a new class of particle,” said Leo Kouwenhoven of Delft University of Tehcnology in the Netherlands, who was not involved in the study. “If you find a new class of particles, that really would add a new chapter to physics.”

Kouwenhoven stressed that further research is necessary to confirm the finding, mainly to rule out the possibility of the proposed Majorana particles obeying the laws of fermions and bosons, which are already characterized.