Synthesis and electronic properties of transition metal oxide core-shell nanowires

This paper reviews our recent progress on the synthesis and transport studies of novel transition metal oxide nanowires, including YBa(2)Cu(3)O(6.66), Fe(3)O(4), La(0.67)Sr(0.33)MnO(3) and PbZr(0.58)Ti(0.42)O(3). Key to our success is the growth of standing 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 have been conducted on both Fe(3)O(4) and La(0.67)Sr(0.33)MnO(3) core-shell nanowires. Devices based on individual Fe(3)O(4) nanowires exhibited room-temperature magnetoresistance of 1.2% under a magnetic field of B = 1.8 T, as a result of tunnelling of spin-polarized electrons across anti-phase boundaries. In addition, devices made of La(0.67)Sr(0.33)MnO(3) nanowires showed a remarkable metal-insulator transition at 325 K, accompanied by room-temperature colossal magnetoresistance (CMR) similar to 10% under a 1 T magnetic field. More interestingly, shape-induced magnetoresistance was also observed at room temperature with the La(0.67)Sr(0.33)MnO(3) nanowires. Our technique could enable various in-depth studies such as phase transition in nanoscale oxides and may pave the way for novel applications of these fascinating materials.