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We have grown epitaxial thin films of multiferroic BiMnO 3 using pulsed laser deposition. The films were grown on SrTiO 3 (001) substrates by ablating a Bi-rich target. Using x-ray diffraction we confirmed that the films were epitaxial and the stoichiometry of the films was confirmed using Auger electron spectroscopy. The films have a ferromagnetic Curie temperature (T C) of 85±5 K and a saturation magnetization of 1 µ B /Mn. The electric polarization as a function of electric field (P − E) was measured using an interdigital capacitance geometry. The P − E plot shows a clear hysteresis that confirms the multiferroic nature of the thin films. PACS numbers: Valid pacs appear here Multiferroic materials are unique in that they exhibit both ferromagnetism and ferroelectricity simultaneously. 1 Such materials may be used to fabricate devices such as magnetic tunnel junctions with electrically tunable tunneling magnetoresistance and multiple state memory elements. 2 The recent interest in multiferroics is fueled both by the potential device applications and questions about the underlying physical principles leading to multiferroism. 3-7 Bulk multiferroic materials are rare, possibly due to conflicting requirements for ferromagnetism (FM) and ferroelectricity (FE). BiMnO 3 is perhaps the most fundamental multi-ferroic and has been referred to as the "hydrogen atom" of multiferroics. 8 In BiMnO 3 (BMO), as in BiFeO 3 , the 6s 2 lone pair on the Bi-ion leads to the displacement of that ion from the centrosymmetric position at the A-site of a perovskite unit cell. The resultant distortion leads to an FM interaction between the Mn-ions at the B-site in BMO. 9,10 In bulk form BMO has been observed to be both FM and FE. 11 Polycrystalline BMO can be grown under high pressure and within a very narrow range of growth conditions. While thin films of BMO have been grown by various groups, few such films have shown magnetic properties similar to bulk BMO and high enough resistivities i.e. low leakage currents to allow clear measurement of FE properties. 12-14 A possible reason for the low resistivities of BMO thin films is the substrate induced strain which exacerbates the growth of a highly distorted perovskite structure. Additionally, recent electron and neutron diffraction data have cast doubt over the purported non-centrosymmetry of the BMO crystal structure 15 and centrosymmetric structures have also been predicted using density functional theory calculations 16. Since a non-centrosymmetric crystal structure is essential for ferroelectricity, the observed ferroelectric behavior of BMO may be due to strain and/or ordered oxygen vacancies. 17,18 BMO has a distorted perovskite-type structure with a = c = 3.935Å935Å (α = γ = 91.4 •) and b = 3.989Å 989Å (β = 91 •). 20 Fig. 1 shows the larger monoclinic unit cell of BMO 9 ; we have used the monoclinic notation to index the x-ray diffraction data of our thin films. Since cubic SrTiO 3 (STO) has a lattice parameter of 3.905Å905Å, BMO grows with an (111) orientation on STO (001) sub-...

BiMnO 3 thin films were deposited on single-crystal (001)-oriented SrTiO 3 substrates by rf-magnetron sputtering method. X-ray diffraction was used to analyze the crystal structure of the thin films, indicating that the films were monoclinic with two dominant orientation relationships along the substrate. The first is (111) BiMnO3 ║ (001) SrTiO3; the second is (222) BiMnO3 ║ (002) SrTiO3; other peaks showed that the films were polycrystalline. The roughness of the films was characterized by AFM. R vs. T was measured from 390 K to 15 K using a Keithley Model 167 Programmable Electrometer . Magnetic characterization was carried out by using a quantum design™ magnetometer for magnetization versus temperature and for hysteresis loops at different temperatures. The saturation magnetic moment of 2.8µ B per Mn ion (still fairly smaller than that of the bulk, 3.6µ B ) was observed at 5 K decreasing with increasing temperature.