Magnetic properties of R2Fe3O7 (R=Yb and Lu)

• Higher Néel temperature of R2Fe3O7 than that of the related multiferroic RFe2O4.
• Magnetic features governed by ferromagnetic–antiferromagnetic competition.
• Magnetic entropy change at around room temperature suitable for application.

We have investigated the magnetic properties of R2Fe3O7 (R=Yb and Lu), which belongs to the homologous family of electronic ferroelectric RFe2O4. Magnetization measurements show ferrimagnetic ordering at the Néel temperature (TN) of ~270 K, which is slightly higher than that of RFe2O4 (TN~230–250 K). Observation of spin glass and exchange bias shows a coexistence of ferromagnetic and antiferromagnetic interactions, similarly to RFe2O4. This situation gives rise to a complex magnetic change and a broad peak of magnetic entropy change. Some characteristics, such as refrigeration temperatures higher than in RFe2O4, seem to offer a possibility of this system to applications.