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Quantum many-body physics

2D or not 2D?

In the fractional quantum Hall effect, the quasiparticles carry fractional charge. But neutral excitations with fractional spin have been elusive in two-dimensional magnets. Is it possible that they have already been observed?

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Figure 1: In a one-dimensional chain of quantum spins (spin S = 1/2) with antiferromagnetic nearest-neighbour interactions, the lowest-lying eigenstates can be described as weakly interacting particles called spinons of spin-1/2.


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McKenzie, R. 2D or not 2D?. Nature Phys 3, 756–758 (2007).

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