Frustration-induced two-dimensional quantum disordered phase in piperazinium hexachlorodicuprate
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 T=1.5 K, the magnetic excitation spectrum is dominated by a single propagating mode with a gap, {Delta}=1 meV, and bandwidth of {approx}1.8 meV in the (h0l) plane. The mode has no dispersion along the b{sup *} direction indicating that neighboring a-c 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 H{sub c1}{approx}7.5 T. Analysis of the neutron-scattering data reveals the important exchange interactions and indicates that some of these are highly frustrated.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 40277677
- Journal Information:
- Physical Review B, Vol. 64, Issue 14; Other Information: DOI: 10.1103/PhysRevB.64.144405; Othernumber: PRBMDO000064000014144405000001; 033138PRB; PBD: 1 Oct 2001; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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