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Princeton University

Princeton scientists discover exotic quantum state of matter

'Quantum Hall-like effect' found in a bulk material without an applied magnetic field
The images observed by the Princeton group provide the first direct evidence for quantum Hall-like behavior without external magnetic fields.
Quantum Hall effect
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Hall effect
Hall effect diagram, showing electron flow (rather than conventional current). Legend: 1. Electrons (not conventional current!) 2. Hall element, or Hall sensor 3. Magnets 4. Magnetic field 5. Power source Description: In drawing "A", the Hall element takes on a negative charge at the top edge (symbolised by the blue color) and positive at the lower edge (red color). In "B" and "C", either the electric current or the magnetic field is reversed, causing the polarization to reverse. Reversing both
In drawing "A", the Hall element takes on a negative charge at the top edge (symbolised by the blue color) and positive at the lower edge (red color). In "B" and "C", either the electric current or the magnetic field is reversed, causing the polarization to reverse. Reversing both current and magnetic field (drawing "D") causes the Hall element to again assume a negative charge at the upper edge.
clipped from: en.wikipedia.org   
Quantum Hall effect
The quantum Hall effect (or integer quantum Hall effect) is a quantum-mechanical version of the Hall effect, observed in two-dimensional electron systems subjected to low temperatures and strong magnetic fields,