Manifestation of the Verwey transition in the tunneling spectra of magnetite nanocrystals
Manifestation of the Verwey transition in the tunneling spectra of magnetite nanocrystals
复制标题
Verwey 跃迁在磁铁矿纳米晶隧道光谱中的表现
DOI：
10.1209/epl/i2003-00141-0
复制
发表时间：
2003
期刊：
影响因子：
1.8
通讯作者：
O. Millo
中科院分区：
文献类型：
--
作者：
P. Poddar;Tcipi Fried;G. Markovich;A. Sharoni;D. Katz;Tommer Wizansky;O. Millo
对单个颗粒和Fe 3 O 4（磁铁矿）纳米晶体阵列进行的Tunneling输运测量为纳米尺度下Verwey金属-绝缘体转变的存在提供了强有力的证据。在100 K附近的电阻测量结果表明，电阻的突然增加，与Verwey转变一致，而电流-电压特性表现出从绝缘体间隙到零偏置电压附近的峰值结构的急剧转变。使用扫描隧道显微镜在孤立粒子上获得的隧道光谱揭示了在低于转变温度的状态密度中的绝缘体状能隙结构，其随着温度的升高而逐渐消失，转变为费米能处的小峰结构。这些数据提供了洞察所发挥的作用，长距离和短距离的电荷订购在Verwey过渡。
Tunneling transport measurements performed on single particles and on arrays of Fe3O4 (magnetite) nanocrystals provide strong evidence for the existence of the Verwey metal-insulator transition at the nanoscale. The resistance measurements on nanocrystal arrays show an abrupt increase of the resistance around 100 K, consistent with the Verwey transition, while the current-voltage characteristics exhibit a sharp transition from an insulator gap to a peak structure around zero bias voltage. The tunneling spectra obtained on isolated particles using a scanning tunneling microscope reveal an insulator-like gap structure in the density of states below the transition temperature that gradually disappeared with increasing temperature, transforming to a small peak structure at the Fermi energy. These data provide insight into the roles played by long- and short-range charge ordering in the Verwey transition.