原子尺度金接触的波长选择性控制
Wavelength-Selective control of Atomic Scale Au Contacts
AI总结：
该研究在机械可控金断点结中，利用530 nm和407 nm波长的光分别驱动金纳米接触的间隙闭合与打开，确立了光选原子漂移作为金属纳米接触可逆控制的机制，可实时定量追踪等离激元辅助的原子重排。
AI中文摘要：
我们在机械可控金断点结中展示了原子运动的波长选择性控制：在λ_form≈530 nm处的激发会驱动间隙闭合与金属桥形成，而在λ_rup≈407 nm处的激发会驱动颈部变细、桥断裂及后续间隙打开。与金属接触中主要通过热膨胀起作用的常规光学开关不同，本实验揭示了不同波长下相反方向的原子漂移。时间分辨电导轨迹使我们能区分两种动力学 regime：隧穿 regime 中，指数电导瞬变测量间隙闭合与打开的间隙坐标漂移速度；金属 regime 中，Sharvin 关系将线性√(G/G₀)瞬变转换为径向颈部生长与变细速度，二者大小相当。这些结果确立了光选原子漂移作为金属纳米接触可逆控制的机制，并提供了实时追踪等离激元辅助原子重排的定量途径。
英文摘要：
We demonstrate wavelength-selective control of atomic motion in a mechanically controllable Au break junction. Excitation at $λ_{\mathrm{form}}\simeq 530~{\rm nm}$ drives gap closure and metallic bridge formation, whereas excitation at $λ_{\mathrm{rup}}\simeq 407~{\rm nm}$ drives neck thinning, bridge rupture, and subsequent gap opening. Unlike conventional optical switching in metallic contacts, where illumination primarily acts via thermal expansion, the present experiment reveals oppositely directed atomic drift at different wavelengths. Time-resolved conductance traces allow us to distinguish two dynamical regimes. In the tunneling regime, exponential conductance transients measure the drift velocity of the gap coordinate for both gap closure and gap opening. In the metallic regime, the Sharvin relation converts linear $\sqrt{G/G_0}$ transients into radial neck-growth and neck-thinning velocities of comparable magnitude. These results establish optically selected atomic drift as a mechanism for reversible control of metallic nanocontacts and provide a quantitative route to follow plasmon-assisted atomic rearrangements in real time.
