Building atoms into functional oxides: Using X-rays coupled to theory in the search for new energy materials

Functional oxides based on the transition metal series display a wide spectrum of remarkable electronic properties including magnetism, superconductivity and metal-insulator transitions, which offer potential important properties for practical applications including colossal responses to external fields, switchable conductivity, and efficient energy conversion. These novel properties arise from the interaction between the charge, orbital, spin, and lattice degrees of freedom. The key to controlling these properties lies in the ability to control the underlying structure. By using epitaxial growth to strain oxide crystal structures, thin film synthesis offers novel route to control oxide structure in ways not attainable in the bulk counterparts. This allows one to access new regions of phase to explore emergent states not present in bulk form. Extending this to ultrathin heterostructures then offers the ability to harness dimensionality as an additional knob to control the interactions of strongly correlated electrons. Here I will highlight our recent work on complex oxide heterostuctures where we are using the connection between theory and experiment to not only create a framework for rational materials design [1-7], but to find pathways to more efficiently synthesize novel materials predicted by theory. Work at Argonne is supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. [1] S.J. May, J.M. Rondinelli, and J.W. Freeland, MRS Bulletin 37, 261 (2012) [2] J. Liu et al. Phys. Rev. Lett. 109, 107402 (2012) [3] J. Liu et al. Phys. Rev. B 83, 161102 (2011). [4] J. Chakhalian et al. Phys. Rev. Lett. 107, 116805 (2011). [5] J.W. Freeland et. al. Europhysics Letters 96, 57004 (2011). [6] J. Chakhalian, J.W. Freeland et. al. Nature Physics 2, 244 (2006). [7] J. Chakhalian, J.W. Freeland et. al. Science 318, 1114 (2007).