Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, Von-Danckelmann-Platz 3, 06120, Halle, Germany.
Interdisziplinäres Zentrum für Materialwissenschaften, Martin-Luther-Universität Halle-Wittenberg, Heinrich-Damerow-Str. 4, 06120, Halle, Germany.
Sci Rep. 2017 Jul 12;7(1):5215. doi: 10.1038/s41598-017-05331-y.
The resistance of the electron gas (2DEG) at the interface between the two band insulators LaAlO (LAO) and SrTiO (STO) typically drops monotonically with temperature and R/T curves during cooling and warm-up look identical for large area structures. Here we show that if the LAO/STO is laterally restricted by nanopatterning the resistance exhibits a temperature anomaly. Warming up nanostructures from low temperatures leads to one or two pronounced resistance peaks between 50 and 100 K not observed for larger dimensions. During cool-down current filaments emerge at the domain walls that form during a structural phase transition of the STO substrate. During warm-up the reverse phase transition can interrupt filaments before the sheet conductivity which dominates at higher temperature is reestablished. Due to the limited number of filaments in a nanostructure this process can result in a complete loss of conductance. As a consequence of these findings the transport physics extracted from experiments in small and large area LAO/STO structures may need to be reconsidered.
在两个带隙绝缘体 LaAlO（LAO）和 SrTiO（STO）之间的界面处，电子气（2DEG）的电阻通常随温度单调下降，并且在冷却和升温过程中，大区域结构的 R/T 曲线看起来相同。在这里，我们表明如果 LAO/STO 通过纳米图案化横向限制，电阻会表现出温度异常。从低温加热纳米结构会导致在 50 和 100 K 之间出现一个或两个明显的电阻峰值，而在较大尺寸下则观察不到。在冷却过程中，电流丝会出现在 STO 衬底结构相变过程中形成的畴壁处。在升温过程中，在恢复主导更高温度的薄片电导率之前，相反的相变可能会中断电流丝。由于纳米结构中电流丝的数量有限，这个过程可能会导致电导完全丧失。由于这些发现，从小面积和大面积 LAO/STO 结构的实验中提取的输运物理性质可能需要重新考虑。
