Like finding a hidden world, physicists dialing up the magnetic field on a semiconducting material have discovered the first in a new family of matter that flowers from the bizarre realm of the quantum scale. In what researchers dubbed the bubble phase of composite fermions, pairs of quasiparticles – particle-like entities arising from the interaction of particles – align in a crystalline pattern, allowing electricity to flow along the edge of the material.
The discovery represents a previously unobserved arrangement of composite fermions, which are entities that behave like particles and are formed from the interaction between electrons and magnetism. The bubble phase of composite fermions falls into a category of matter properly called topological insulators, which denotes that electricity flows only along the outer surface or edge of the material, while the cross-section does not conduct electricity. While dozens of topological insulators have been discovered by condensed matter physicists, the combined paired and periodic structure of the bubble phase represents an entirely new family or sub-category of “highly correlated topological phases” that had been theorized but not previously observed.
“As the first member of a new family of highly correlated topological phases, this new phase expands our understanding and offers a glimpse of the role of electronic interactions in generating higher order correlations in electronic systems,” said Gábor Csáthy, a Purdue University professor and head of the Department of Physics and Astronomy.