Scientists detect mysterious new state of matter

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London: An international team of scientists has successfully detected a mysterious new state of matter that causes electrons -- thought to be nature's indivisible building blocks -- to break into pieces.

The state, known as a quantum spin liquid, was found in a two-dimensional material with a structure similar to graphene. 

First predicted 40 years ago, quantum spin liquids were thought to be hiding in certain magnetic materials, but had not been conclusively sighted in nature.

"This is a new quantum state of matter, which has been predicted but hasn't been seen before," said Johannes Knolle from Cambridge University, one of the co-authors of the study published recently in the journal Nature Materials.

In a typical magnetic material, the electrons each behave like tiny bar magnets. And when a material is cooled to a low enough temperature, they will order themselves so that all the north magnetic poles point in the same direction.

But in a material containing a spin liquid state, even if that material is cooled to absolute zero, the bar magnets would not align but form an entangled soup caused by quantum fluctuations.

The researchers used neutron scattering techniques to look for experimental evidence of fractionalisation in crystals of ruthenium chloride (RuCl3) to measure the first signatures of fractional particles known as Majorana fermions. 

The researchers tested the magnetic properties of the RuCl3 crystals by illuminating them with neutrons, and observing the pattern of ripples that the neutrons produced on a screen.

A regular magnet would create distinct sharp spots, but it was a mystery what sort of pattern the Majorana fermions in a quantum spin liquid would make. 

The earlier theoretical prediction of distinct signatures matched well with what experimentalists observed on the screen, providing for the first time direct evidence of a quantum spin liquid and the fractionalisation of electrons in a two dimensional material.