Magnetism-induced ferroelectric polarization in the c-axis-oriented orthorhombic HoMnO3 thin films.

The magnetism-induced ferroelectricity in the E-type orthorhombic HoMnO3 (o-HMO) films grown on Nb-doped and undoped SrTiO3(001) substrates was studied. The temperature dependent magnetization in these films evidently exhibits an antiferromagnetic ordering around 44 K and an anomalous second magnetic ordering along the c-axis near 35 K. Interestingly, at this anomalous transition temperature, an associated ferroelectric polarization was probed by the P-E hysteresis measurements, indicating the intimated coupling between the ferroelectric response and the reordering of Mn spins, which has never been disclosed previously by dielectric constant measurements. [ABSTRACT FROM AUTHOR]