Successive phase transitions and extended spin-excitation continuum in the S=1/2 triangular-lattice antiferromagnet Ba3CoSb2O9.
Using magnetic, thermal, and neutron measurements on single-crystal samples, we show that Ba3CoSb2O9 is a spin-1/2 triangular-lattice antiferromagnet with the c axis as the magnetic easy axis and two magnetic phase transitions bracketing an intermediate up-up-down phase in magnetic field applied along the c axis. A pronounced extensive neutron-scattering continuum above spin-wave excitations, observed below T(N), implies that the system is in close proximity to one of two spin-liquid states that have been predicted for a 2D triangular lattice.
Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996-1200, USA. hzhou10@utk.edu
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Zhou
Cenke
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Xu
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Hallas
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Silverstein
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Wiebe
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Umegaki
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Yan
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Murphy
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Park
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Qiu
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Copley
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Gardner
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Takano