Growth and multiferroic properties of hexagonal HoMnO3 films

Hexagonal, twin-free HoMnO3 (0001) films of 25-240 nm thickness were grown epitaxially on Y2O3:ZrO2(111) substrates using pulsed laser deposition. Ferroelectric polar order and Mn3+ antiferromagnetism were observed by optical second harmonic generation. Magnetization data reveal Ho3+ ordering which is, with subtle deviations, similar to that of bulk crystals. However, three phase transitions below 6 K and thermal hysteresis of magnetization at T < 42 K were detected. (c) 2007 American Institute of Physics.