Magnetic excitations in the spin-1/2 tetramer substance Cu2114Cd11B2O6 obtained by inelastic neutron scattering experiments.

We performed inelastic neutron scattering experiments on Cu2114Cd11B2O6 powder. The magnetic excitations at low temperatures are similar to those of the interacting spin-1/2 tetramers in the ordered state. The weak excitations existing above 3 meV suggest that the Higgs mode appears in Cu2CdB2O6 at ambient pressure and zero magnetic field. We evaluated J1=27.3±1.0 and J2=-14.0±1.4 meV for the intratetramer interactions and J3=-0.4±0.2 and J4=1.4±0.2meV for the intertetramer interactions. The spin gap in the isolated spin tetramer was calculated to be 1.6 meV, which is less than the effective intertetramer interaction value (3.6±0.8 meV). Therefore, antiferromagnetic long-range order is possible, although the ground state of the isolated spin tetramer is the spin-singlet state. We discuss the temperature dependence of the magnetic excitations. [ABSTRACT FROM AUTHOR]