Magnetic structure of Cu2CdB2O6 having magnetization plateau and antiferromagnetic long-range order

The cuprate Cu2CdB2O6 exhibits a quantum-mechanical 1/2 magnetization plateau and classical antiferromagnetic long-range order (AF-LRO). Two Cu sites (Cul and Cu2) exist and have spin-1/2. It was speculated previously that spins on the Cul sites were in a nearly singlet state, and that spins on the Cu2 sites formed AF-LRO in weak magnetic fields and were almost saturated in fields of the magnetization plateau. We show the magnetic structure of Cu2114Cd11B2O6 determined using neutron powder diffraction measurements. Contrary to that previous speculation, both the Cul and Cu2 spins have large magnetic moments in the ordered state. We re-considered the spin state in Cu2CdB2O6.