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

Abstract

This paper reviews our recent progress on the synthesis andtransport studies of novel transition metal oxide nanowires, includingYBa2Cu3O6.66,Fe3O4,La0.67Sr0.33MnO3 and PbZr0.58Ti0.42O3. Key to our success is the growth of standing single-crystalline MgO nanowires, which workedas excellent templates for epitaxial deposition of the desired transition metal oxides and ledto high-quality core–shell nanowires. Transport studies have been conducted on bothFe3O4 and La0.67Sr0.33MnO3 core–shell nanowires. Devices based on individualFe3O4 nanowires exhibited room-temperature magnetoresistance of 1.2% under a magnetic field ofB = 1.8 T, asa result of tunnelling of spin-polarized electrons across anti-phase boundaries. In addition, devices madeof La0.67Sr0.33MnO3 nanowires showed a remarkable metal–insulator transition at 325 K,accompanied by room-temperature colossal magnetoresistance (CMR)∼10% under a 1 T magnetic field. More interestingly, shape-inducedmagnetoresistance was also observed at room temperature with theLa0.67Sr0.33MnO3 nanowires. Our technique could enable various in-depth studies such as phase transition innanoscale oxides and may pave the way for novel applications of these fascinatingmaterials.