O*

The well-studied compounds Sr₃Cr₂O₈ and Ba₃Cr₂O₈ are insulating dimerized antiferromagnets with magnetic ions, Cr⁵⁺. These spin ½ ions have a strong intradimer antiferromagnetic coupling, which leads to a singlet ground state and gapped triplet states. Spontaneous long-range ordering occurs upon applying an external magnetic field. We investigate the magnetic properties of Sr₃Cr₂O₈ by introducing chemical disorder upon replacing Sr by Ba. We performed heat capacity and ultrasound velocity measurements in high magnetic fields up to 30 T and 60 T respectively, in order to map the magnetic phase transitions. Moreover, electron spin resonance (ESR) measurements were done to investigate different transitions between the singlet ground state and gapped triplet states.