Observation of structural anomaly and low-field magnetocaloric effect in Cu2OSeO3.

• Structural and magnetic properties of skyrmionic system, Cu 2 OSeO 3 are investigated. • Thermal hysteresis between FC and FCH data is observed. • Lattice distortion at the magnetic transition is noticed. • Large MCE is found near the ferrimagnetic transition for a small change in magnetic field. • The observed anomalous change in Cu(1)-Cu(2) distances tune the strength of the magnetic exchange interactions. [Display omitted] We report here the detailed investigation on structural and magnetic behavior of the polycrystalline sample of Cu 2 OSeO 3. The Mott insulator Cu 2 OSeO 3 is a fascinating material showing skyrmionic state and magneto-electric coupling. We observe clear signature of thermal hysteresis between field-cooled and field-cooled heating data in the low-field magnetization versus temperature curve just below the magnetic ordering temperature of T C ~ 60 K. Temperature dependent powder x-ray diffraction data indicate the presence of lattice anomaly below T C. The sample also shows reasonable value of conventional magnetocaloric effect for small value of applied magnetic field, which can be related to the change in the magnetic structure with field. [ABSTRACT FROM AUTHOR]