Transition Metal Oxide Core−Shell Nanowires:  Generic Synthesis and Transport Studies

A generic non-equilibrium synthesis technique has been developed to produce novel transition metal oxide nanowires, including YBa 2 Cu 3 O 6.66, La 0.67 Ca 0.33 MnO 3, PbZr 0.58 Ti 0.42 O 3, and Fe 3 O 4 . Key to our success is the growth of vertically aligned single-crystalline MgO nanowires, which worked as excellent templates for epitaxial deposition of the desired transition metal oxides and led to high-quality core−shell nanowires. Transport studies on La 0.67 Ca 0.33 MnO 3 nanowires have revealed the remarkable persistence of metal−insulator transition and magnetoresistance down to nanometer scale. Our technique will enable various in-depth studies such as phase transition in nanoscale oxides and may pave the way for novel applications of these fascinating materials.