Stabilizing new bismuth compounds in thin film form

Growth of unexpected phases from a composite target of BiFeO₃:BiMnO₃ and/or BiFeO₃:BiCrO₃ has been explored using pulsed laser deposition. The Bi₂FeMnO₆ tetragonal phase can be grown directly on SrTiO₃ (STO) substrate, while two phases (S1 and S2) were found to grow on LaAlO₃ (LAO) substrates with narrow growth windows. However, introducing a thin CeO₂ buffer layer effectively broadens the growth window for the pure S1 phase, regardless of the substrate. Moreover, we discovered two new phases (X1 and X2) when growing on STO substrates using a BiFeO₃:BiCrO₃ target. Pure X2 phase can be obtained on CeO₂-buffered STO and LAO substrates. This work demonstrates that some unexpected phases can be stabilized in a thin film form by using composite perovskite BiRO₃ (R = Cr, Mn, Fe, Co, Ni) targets. Furthermore, it also indicates that CeO₂ can serve as a general template for the growth of bismuth compounds with potential room-temperature multiferroicity.