Cu{sub 2}(1,4-diazacycloheptane){sub 2}Cl{sub 4}: Spin-ladder system with competing interactions (abstract)
- Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218 (United States)
- Argonne National Labs, Argonne, Illinois 60439 (United States)
The material Cu{sub 2}(1,4-diazacycloheptane){sub 2}Cl{sub 4} consists of well-separated ladderlike chains of Cu atoms that undergo spontaneous dimerization leading to a singlet ground state. Previous measurements have shown that for T{le}0.7 K, this singlet ground state exists up to a field H{sub C}=6.7. Here we report on heat capacity, C{sub p}(H,T), and neutron scattering studies of this material. For T{lt}8 K, C{sub p}(H=0,T){proportional_to}T{sup {minus}3/2}exp{l_brace}{minus}{Delta}/T{r_brace} with an activation energy {Delta}=9.8 K. C{sub p}(H,T) shows a finite-{ital T} transition for H{gt}H{sub C}, presumably to a canted state. Inelastic neutron scattering on powder samples at H=0 shows a gap of 0.8 meV and a bandwidth for the excitations of 0.6 meV. These excitations exhaust the total moment sum rule, and hence the measured triplet band dominates the magnetic fluctuation spectrum. Comparison of the data with exact diagonalization of finite spin chains shows that the system appears to be close to a spin ladder, but with an additional, weak interrung interaction. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 554264
- Report Number(s):
- CONF-961141-; ISSN 0021-8979; TRN: 98:000875
- Journal Information:
- Journal of Applied Physics, Vol. 81, Issue 8; Conference: 41. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 12-15 Nov 1996; Other Information: PBD: Apr 1997
- Country of Publication:
- United States
- Language:
- English
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