论文标题
Crystalline NBO $ _2 $中焦耳加热引起的电阻率转换的机制
Mechanism of the Resistivity Switching Induced by the Joule Heating in Crystalline NbO$_2$
论文作者
论文摘要
最近，NBO $ _2 $中的回忆电运输特性引起了人们对神经形态计算的有希望的应用的广泛关注。在辩论的中心是金属到绝缘体转变（MIT）是起源于结构失真（PEIERLS）还是电子相关性（MOTT）。通过实验和第一原理计算的输入，我们开发了一个热力学模型，该模型植根于由$ 2^{nd} $ order peierls不稳定驱动的MIT方案。我们发现，由于NB-NB二聚体的逐渐弱化，带隙随温度变化而变化的条带隙可以准确地拟合的温度依赖性。因此，可以通过局部焦耳加热引起的无二聚体金属结构域来理解电阻率转换。在求解热方程时，我们发现如果施加的电压超过阈值，则无法达到稳态，从而导致在高压和电流状态下观察到混乱的行为。通过Ginzburg-Landau理论和Joule加热方程，可以通过实验模拟并直接验证金属域在偏置电压下的演变。
Recently the memristive electrical transport properties in NbO$_2$ have attracted much attention for their promising application to the neuromorphic computation. At the center of debates is whether the metal-to-insulator transition (MIT) originates from the structural distortion (Peierls) or the electron correlation (Mott). With inputs from experiments and first principles calculations, we develop a thermodynamical model rooted in the scenario of the MIT driven by a $2^{nd}$ order Peierls instability. We find that the temperature dependence of the electrical conductivity can be accurately fit by the band gap varying with temperature due to the gradual weakening of the Nb-Nb dimers. The resistivity switching can consequently be understood by dimer-free metallic domains induced by local Joule heating. In solving the heat equation, we find that the steady state can not be reached if the applied voltage exceeds a threshold, resulting in the chaotic behavior observed in the high voltage and current states. With the Ginzburg-Landau theory and the Joule heating equation, the evolution of the metallic domains under bias voltage can be simulated and directly verified by experiments.
