Comparison of the Structural, Magnetic and Piezoelectric Properties of BiFeO$_{3}$ and BiCrO$_{3}$ Thin Films

Multiferroic BiCrO$_{3}$ is a perovskite-structured oxide that is antiferroelectric and antiferromagnetic at low temperature [1,2] and is structurally very similar to the better studied BiFeO$_{3}$. Here we present a comparative study of the structural, magnetic and piezoelectric properties of BiFeO$_{3}$ and BiCrO$_{3}$ thin films. Highly strained BiFeO$_{3}$ films grown on LaAlO$_{3}$ substrates adopt the nearly tetragonal T' polymorph (c/a $\sim$ 1.25), however, they are rarely structurally uniform, instead tilted T' and tilted S'-polymorphs (c/a $\sim$ 1.09) coexist in the form of stripe patterns [3,4]. More importantly we find that the presence of S' is a prerequisite for ferroelectric switching [4,5]. Here, we extend this work to BiCrO$_{3}$ films grown on various substrates. Synchrotron and neutron measurements allow us to carefully characterize both the structural and magnetic properties of BiCrO$_{3}$ thin films. This research was supported in part by the U.S. DOE-BES, Materials Sciences and Engineering Division, and performed in part at the CNMS, ShaRE, and APS DOE-BES user facilities. [1] F. Sugawara et al., J. Phys. Soc. Jpn. \textbf{25}, 1553 (1968) [2] D.H. Kim et al., Appl. Phys. Lett. \textbf{89}, 162904 (2006) [3] R.J. Zeches et al., Science \textbf{326}, (2009) [4] C. Beekman et al., Adv. Mater (in press) [5] W. Siemons et al., J Phys. D (in press)