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Title:
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Quantum criticality in an organic magnet |
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Author:
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Stone, M.B.; Broholm, C.; Reich, D.H.; Tchernyshyov, O.; Vorderwisch, P.; Harrison, N. |
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Abstract:
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Exchange interactions between S=½ sites in piperazinium hexachlorodicuprate produce a frustrated bilayer magnet with a singlet ground state. We have determined the field-temperature phase diagram by high field magnetization and neutron scattering experiments. There are two quantum critical points: Hc1=7.5 T separates a quantum paramagnet phase from a three dimensional, antiferromagnetically ordered state while Hc2=37 T marks the onset of a fully polarized state. The ordered phase, which we describe as a magnon Bose-Einstein condensate (BEC), is embedded in a quantum critical regime with short range correlations. A low temperature anomaly in the BEC phase boundary indicates that additional low energy features of the material become important near Hc1. |
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URI:
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http://jhir.library.jhu.edu/handle/1774.2/33751
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Date:
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2006-06-30 |
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Citation:
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Physical Review Letters 30 June 2006, vol.96, no.25, pp. 257203/1-4
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Subject:
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high field magnetization
field-temperature phase diagram
singlet ground state
frustrated bilayer magnet
piperazinium hexachlorodicuprate
organic magnet
quantum criticality
high field magnetization
paramagnetic-antiferromagnetic transitions
fully polarized state
paramagnetic materials
neutron diffraction
molecular magnetism
magnons
exchange interactions (electron)
antiferromagnetic materials
magnon Bose-Einstein condensate
quantum critical regime
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