Probing local moments in nanographenes with electron tunneling spectroscopy

IF 8.7 2区工程技术 Q1 CHEMISTRY, PHYSICAL

Progress in Surface Science Pub Date : 2020-12-01 DOI:10.1016/j.progsurf.2020.100595

R. Ortiz , J. Fernández-Rossier

{"title":"Probing local moments in nanographenes with electron tunneling spectroscopy","authors":"R. Ortiz , J. Fernández-Rossier","doi":"10.1016/j.progsurf.2020.100595","DOIUrl":null,"url":null,"abstract":"<div>The emergence of local moments in graphene zigzag edges, grain boundaries, vacancies and sp3 defects has been widely studied theoretically. However, conclusive experimental evidence is scarce. Recent progress in on-surface synthesis has made it possible to create nanographenes, such as triangulenes, with local moments in their ground states, and to probe them using scanning tunneling microscope (STM) spectroscopy. Here we review the application of the theory of sequential and cotunneling transport to relate the <math><mrow><mi>dI</mi><mo>/</mo><mi>dV</mi></mrow></math> spectra with the spin properties of nanographenes probed by STM. This approach permits us to connect the <math><mrow><mi>dI</mi><mo>/</mo><mi>dV</mi></mrow></math> with the many-body energies and wavefunctions of the graphene nanostructures. We apply this method describing the electronic states of the nanographenes by means of exact diagonalization of the Hubbard model within a restricted Active Space. This permits us to provide a proper quantum description of the emergence of local moments in graphene and its interplay with transport. We discuss the results of this theory in the case of diradical nanographenes, such as triangulene, rectangular ribbons and the Clar’s goblet, that have been recently studied experimentally by means of STM spectroscopy. This approach permits us to calculate both the <math><mrow><mi>dI</mi><mo>/</mo><mi>dV</mi></mrow></math> spectra, that yields excitation energies, as well as the atomically resolved conductivity maps, that provide information on the wavefunctions of the collective spin modes.</div>","PeriodicalId":416,"journal":{"name":"Progress in Surface Science","volume":"95 4","pages":"Article 100595"},"PeriodicalIF":8.7000,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/j.progsurf.2020.100595","citationCount":"12","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Progress in Surface Science","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0079681620300241","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}

引用次数: 12

Abstract

The emergence of local moments in graphene zigzag edges, grain boundaries, vacancies and sp³ defects has been widely studied theoretically. However, conclusive experimental evidence is scarce. Recent progress in on-surface synthesis has made it possible to create nanographenes, such as triangulenes, with local moments in their ground states, and to probe them using scanning tunneling microscope (STM) spectroscopy. Here we review the application of the theory of sequential and cotunneling transport to relate the $dI / dV$ spectra with the spin properties of nanographenes probed by STM. This approach permits us to connect the $dI / dV$ with the many-body energies and wavefunctions of the graphene nanostructures. We apply this method describing the electronic states of the nanographenes by means of exact diagonalization of the Hubbard model within a restricted Active Space. This permits us to provide a proper quantum description of the emergence of local moments in graphene and its interplay with transport. We discuss the results of this theory in the case of diradical nanographenes, such as triangulene, rectangular ribbons and the Clar’s goblet, that have been recently studied experimentally by means of STM spectroscopy. This approach permits us to calculate both the $dI / dV$ spectra, that yields excitation energies, as well as the atomically resolved conductivity maps, that provide information on the wavefunctions of the collective spin modes.

查看原文本刊更多论文

用电子隧穿光谱探测纳米石墨烯的局部矩

石墨烯之字形边缘、晶界、空位和sp3缺陷中局部矩的出现已经得到了广泛的理论研究。然而，结论性的实验证据很少。表面合成的最新进展使得制造纳米石墨烯，如三角烯，在其基态具有局部矩，并使用扫描隧道显微镜(STM)光谱来探测它们成为可能。本文综述了序贯输运理论和共隧道输运理论的应用，将dI/dV光谱与STM探测的纳米石墨烯的自旋性质联系起来。这种方法允许我们将dI/dV与石墨烯纳米结构的多体能量和波函数连接起来。我们应用这种方法，通过哈伯德模型的精确对角化，在一个受限的活动空间内描述纳米石墨烯的电子态。这使我们能够对石墨烯中局部矩的出现及其与输运的相互作用提供适当的量子描述。我们讨论了这一理论在双自由基纳米石墨烯的情况下的结果，如三角烯，矩形带和克拉尔杯，最近已经通过STM光谱的实验研究。这种方法允许我们计算产生激发能的dI/dV光谱，以及提供关于集体自旋模式波函数信息的原子分辨电导率图。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Progress in Surface Science 工程技术-物理：凝聚态物理

CiteScore

11.30

自引率

0.00%

发文量

审稿时长

3 months

期刊介绍： Progress in Surface Science publishes progress reports and review articles by invited authors of international stature. The papers are aimed at surface scientists and cover various aspects of surface science. Papers in the new section Progress Highlights, are more concise and general at the same time, and are aimed at all scientists. Because of the transdisciplinary nature of surface science, topics are chosen for their timeliness from across the wide spectrum of scientific and engineering subjects. The journal strives to promote the exchange of ideas between surface scientists in the various areas. Authors are encouraged to write articles that are of relevance and interest to both established surface scientists and newcomers in the field.