手性金纳米晶体中的对映体选择性磁电阻：通过磁场控制表面电势
Enantiomer-Selective Magnetoresistance in Chiral Gold Nanocrystals by Magnetic Control of Surface Potentials
AI总结：
本研究在手性金纳米晶体中发现对映体选择性磁电阻效应，通过磁场方向控制表面电势实现电阻的数十倍调制，并可通过表面化学调节，为手性纳米电子学提供新机制。
摘要：
手性纳米材料为新型电子和化学应用提供了引人入胜的可能性。在此，我们报告了在手性金纳米晶体中发现的一种对映体选择性磁电阻效应。基于使用氨基酸定向合成对纳米晶体手性形貌的精确控制，我们证明外部磁场能够以对映体特异的方式显著调节电阻。对于给定的对映体，一个方向的磁场会使电阻改变数十倍，而相反方向的磁场则使其保持不变。这种不对称响应对于相反的对映体会反转，并且通过导电原子力显微镜在单个纳米晶体中以及在固态器件的纳米晶体薄膜中均得到了重现。我们将此现象归因于一种由手性驱动的电荷泵浦效应，其中手性形貌与磁场之间的相互作用选择性地修饰了表面电势。磁电阻的大小和符号可以通过纳米晶体的表面化学进一步调节，正如通过硫化物处理所展示的那样。我们的发现揭示了一种新的手性依赖磁电阻形式，不同于先前已知的效应，如手性诱导的自旋选择性和电磁手性各向异性。利用磁场远程控制手性纳米结构表面电势的能力，可能为催化、药物递送和纳米电子学带来新的方法。
英文摘要：
Chiral nanomaterials offer intriguing possibilities for novel electronic and chemical applications. Here, we report the discovery of an enantiomer-selective magnetoresistance effect in chiral gold nanocrystals. Based on precise control of nanocrystal chiral morphology using amino acid-directed synthesis, we demonstrate that an external magnetic field can dramatically modulate resistance in an enantiomer-specific manner. For a given enantiomer, a magnetic field in one direction alters the resistance by dozens of times, while the opposite field direction leaves it unchanged. This asymmetric response reverses for the opposite enantiomer and are reproduced in both single nanocrystals by conduction atomic force microscopy and nanocrystal thin films in solid state devices. We attribute this phenomenon to a chirality-driven charge pumping effect, where the interplay between the chiral morphology and the magnetic field selectively modifies the surface potential. The magnitude and sign of the magnetoresistance can be further tuned by the surface chemistry of the nanocrystal, as demonstrated through sulfide treatment. Our findings reveal a new form of chirality-dependent magnetoresistance, distinct from previously known effects such as chirality-induced spin selectivity and electric magnetochiral anisotropy. The ability to remotely control surface potentials of chiral nanostructures using magnetic fields could enable novel approaches in catalysis, drug delivery, and nanoelectronics.
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