Field induced magnetic ordering and single ion anisotropy in the quasi one dimensional Haldane chain compound SrNi2V2O8 A single crystal investigation

摘要

Field induced magnetic ordering in the Haldane chain compound SrNi2V2O8 and the effect of anisotropy have been investigated using single crystals. Static susceptibility, inelastic neutron scattering, high field magnetization, and low temperature heat capacity studies confirm a nonmagnetic spin singlet ground state and a gap between the singlet ground state and triplet excited states. The intrachain exchange interaction is estimated to be J amp; 8764;8.9 0.1 meV. Splitting of the dispersions into two modes with minimum energies 1.57 and 2.58 meV confirms the existence of single ion anisotropy D Sz 2. The value of D is estimated to be amp; 8722;0.51 0.01 meV and the easy axis is found to be along the crystallographic c axis. Field induced magnetic ordering has been found with two critical fields amp; 956;0Hc amp; 8869;c 12.0 0.2 T and amp; 956;0Hc amp; 8741;c 20.8 0.5 T at 4.2 K . Field induced three dimensional magnetic ordering above the critical fields is evident from the heat capacity, susceptibility, and high field magnetization study. The phase diagram in the H T plane has been obtained from the high field magnetization. The observed results are discussed in the light of theoretical predictions as well as earlier experimental reports on Haldane chain compounds