Electrostatic modulation of conductivity in Nd/sub 1.2/Ba/sub 1.8/Cu/sub 3/O/sub y/ thin films
Electrostatic modulation of conductivity in Nd/sub 1.2/Ba/sub 1.8/Cu/sub 3/O/sub y/ thin films
复制标题
Nd/sub 1.2/Ba/sub 1.8/Cu/sub 3/O/sub y/薄膜中电导率的静电调制
DOI：
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发表时间：
2005
影响因子：
1.8
通讯作者：
R. Vaglio
中科院分区：
文献类型：
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作者：
A. Cassinese;G. M. De Luca;A. Gambardella;A. Prigiobbo;M. Salluzzo;R. Vaglio
通过改变每个CuO/sub 2/平面的载流子数n/sub h/可以改变HTS性能。高温超导相图（温度与孔数）的惊人的普遍性，提出了许多关于这些材料的物理学的基本方面的问题，并在同一时间，提供了一个有趣的工具，用于控制其传输特性和实现新的设备。利用场效应器件对生长在SrTiO/sub 3/衬底上的Nd/sub 1.2/Ba/sub 1.8/Cu/sub 3/O/sub 7/外延薄膜的表面载流子数进行了修正。电影调查低于9 u.c.提出了一个可变范围跳跃莫特绝缘体温度依赖的电阻率类似于其他绝缘体属于家庭的强相关系统。栅极可以通过Al/sub 2/O/sub 3/层（栅极向上配置）或通过在SrTiO/sub 3/衬底的背侧上施加电场（栅极向下配置）施加在顶层上。该器件是由一个完全在原位技术，避免顶面和层间杂质制造。在这里，我们报告的I-V特性和电阻测量，主要是与栅极向下配置绝缘样品。特别感兴趣的是致力于了解在这种化合物中可实现的最大调制。关于超导样品（10 u.c.）也报道了超导体-绝缘体转变的可能性。
HTS properties can be modified by changing the carrier number n/sub h/ per CuO/sub 2/ plane. The astonishing generality of the HTS phase diagram (temperature vs. number of holes), poses many questions concerning the fundamental aspects of the physics of such materials and, at the same time, offers an interesting instrument for the control of their transport properties and for the realization of new devices. Using field effect devices, we have modified the number of carriers in the surface layers of Nd/sub 1.2/Ba/sub 1.8/Cu/sub 3/O/sub 7/ epitaxial films, grown on SrTiO/sub 3/ substrate, having thickness ranging between 4 and 10 unit cells (u.c.). The films investigate below 9 u.c. present a Variable Range Hopping Mott-insulator temperature dependence of the resistivity analogous to other insulators belonging to the families of strongly correlated systems. The gate can be applied both on the top layer through an Al/sub 2/O/sub 3/ layer (gate up configuration) or by applying the electrical field on the back side of the SrTiO/sub 3/ substrate (gate down configuration). The devices are fabricated by a completely in situ technique, avoiding superface and inter-layers impurities. Here we report on the I-V characteristics and on resistive measurements obtained mainly with gate down configuration on insulating samples. Particular interest was devoted to the understanding of the maximum modulation achievable in this compound as well. Considerations on superconducting samples (10 u.c.) are also reported as well as on the possibility on the possibilities of superconductor-insulator transitions.