Origin of metamagnetism in skyrmion host Cu[Formula: see text] OSeO[Formula: see text]

Skyrmion host chiral Cu[Formula: see text] OSeO[Formula: see text] has attracted researchers due to several intriguing properties. Observation of metamagnetism in low-temperature and low-field makes the magnetic properties of Cu[Formula: see text] OSeO[Formula: see text] more complex. Here, we present an investigation on metamagnetism in Cu[Formula: see text] OSeO[Formula: see text] by analyzing its structural and magnetic properties. Study of magnetic properties reveal spin-flip of one of the Cu[Formula: see text] ions, embedded in square pyramidal CuO[Formula: see text] polyhedra, due to the development of strain in low-temperature and low-field regime. The spin-flip is found to be the main reason for field-induced first-order metamagnetic transition. Magnetic phase diagram of Cu[Formula: see text] OSeO[Formula: see text] has been constructed with the help of magnetization analyses. It is argued that the metamagnetic hysteretic field region may be low-temperature skyrmion phase with additional spiral and tilted-conical phases. A tricritical point has been observed in the phase diagram at which first-order metamagnetic hysteretic field range ceases to exist.