Magnetic properties and spin reorientation of hexagonal HoFeO3 thin films

We present structural, magnetic, and optical properties of hexagonal HoFeO3/Al2O3 thin films deposited by Magnetron Sputtering. The x-ray diffraction patterns of HoFeO3 thin films show the c-planes of a hexagonal structure. The magnetization data display an antiferromagnetic transition temperature, TN-120 +/- 5 K and the magnetization-field hysteresis loops were measured below 100 K, confirming a weak ferromagnetism arising from a spin canting of the Fe3+ moments. The magnetization data also show an anomaly around-40 K due to a spin-reorientation transition caused by the Ho3+-Fe3+ interactions. We observed comparable magnetization along the ab plane and c axis although the spin canting of Fe3+ sites has a preferential component along the c axis, suggesting that the Ho3+- Fe3+ interactions dominate in the low temperature magnetic structures of hexagonal-HoFeO3. The observed electronic excitations at similar to 2.29, 2.87, 3.82, 4.79, and 6.53 eV have been assigned to the Fe3+ d to d on-site as well as O 2p to Fe 3d, Ho 6s, and 5d charge-transfer excitations, respectively. The room temperature energy band gap of the hexagonal-HoFeO3 thin film was measured to be similar to 1.99 +/- 0.04 eV.

Automated summary

The study reveals that hexagonal HoFeO3 thin films exhibit weak ferromagnetism at low temperatures and a spin reorientation transition caused by Ho3+-Fe3+ interactions. Electronic excitations include Fe3+ d to d on-site transitions and charge transfer excitations from O 2p to Fe 3d, Ho 6s, and 5d.