Mitra Gautam, Low Jonathan Z, Wei Sujun, Francisco Karol R, Deffner Michael, Herrmann Carmen, Campos Luis M, Scheer Elke
Department of Physics, University of Konstanz, 78457 Konstanz, Germany.
Department of Chemistry, Columbia University, New York, New York 10027, United States.
Nano Lett. 2022 Jul 27;22(14):5773-5779. doi: 10.1021/acs.nanolett.2c01199. Epub 2022 Jul 18.
We report transport measurements on tunable single-molecule junctions of the organic perchlorotrityl radical molecule, contacted with gold electrodes at low temperature. The current-voltage characteristics of a subset of junctions shows zero-bias anomalies due to the Kondo effect and in addition elevated magnetoresistance (MR). Junctions without Kondo resonance reveal a much stronger MR. Furthermore, we show that the amplitude of the MR can be tuned by mechanically stretching the junction. On the basis of these findings, we attribute the high MR to an interference effect involving spin-dependent scattering at the metal-molecule interface and assign the Kondo effect to the unpaired spin located in the center of the molecule in asymmetric junctions.
我们报告了在低温下与金电极接触的有机三氯甲基自由基分子的可调谐单分子结的输运测量结果。一部分结的电流-电压特性显示出由于近藤效应导致的零偏置异常，此外还有增强的磁电阻（MR）。没有近藤共振的结显示出更强的MR。此外，我们表明可以通过机械拉伸结来调节MR的幅度。基于这些发现，我们将高MR归因于涉及金属-分子界面处自旋相关散射的干涉效应，并将近藤效应归因于不对称结中位于分子中心的未配对自旋。
