# Condensed-Matter Physics & Materials Science Seminar

## "Spinons in the S=1/2 Heisenberg antiferromagnet on kagome"

#### Presented by Oleg Tchernyshyov, Johns Hopkins University

Thursday, November 17, 2011, 1:30 pm — Small Seminar Room, Bldg. 510

Spin excitations in a magnet with ordered moments are magnons, quantized spin waves that behave like particles with integer spin and Bose-Einstein statistics. A magnet lacking long-range order cannot support spin waves and may have unusual magnetic excitations with noninteger spin and different statistics. Heisenberg antiferromagnets with spins of length $S=1/2$ on kagome (a network of corner-sharing triangles) have emerged as a leading candidate for novel quantum physics. Magnetic excitations in this system are spinons, particles with spin 1/2 and fermionic statistics. Thanks to exchange-mediated attraction, spinons form small pairs with spin 0. The spin gap is set by the binding energy of a pair, about 0.06 of the exchange constant.

Hosted by: Alexei Tsvelik

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