Abstract
Piperazinium hexachlorodicuprate is shown to be a frustrated quasi-two-dimensional quantum Heisenberg antiferromagnet with a gapped spectrum. Zero-field inelastic neutron scattering and susceptibility and specific- heat measurements as a function of applied magnetic field are presented. At (formula presented) the magnetic excitation spectrum is dominated by a single propagating mode with a gap, (formula presented) and bandwidth of (formula presented) in the (formula presented) plane. The mode has no dispersion along the (formula presented) direction indicating that neighboring (formula presented) planes of the triclinic structure are magnetically decoupled. The heat capacity shows a reduction of the gap as a function of applied magnetic field in agreement with a singlet-triplet excitation spectrum. A field-induced ordered phase is observed in heat capacity and magnetic susceptibility measurements for magnetic fields greater than (formula presented) Analysis of the neutron-scattering data reveals the important exchange interactions and indicates that some of these are highly frustrated.
Original language | English |
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Journal | Physical Review B - Condensed Matter and Materials Physics |
Volume | 64 |
Issue number | 14 |
DOIs | |
State | Published - 2001 |
Externally published | Yes |