Independent and coherent transitions between antiferromagnetic states of few-molecule systems

Claire Besson, Philipp Stegmann, Michael Schnee, Zeila Zanolli, Simona Achilli, Nils Wittemeier, Asmus Vierck, Robert Frielinghaus, Paul Kögerler, Janina Maultzsch, Pablo Ordejón, Claus M. Schneider, Alfred Hucht, Jürgen König, Carola Meyer

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Spin-electronic devices are poised to become part of mainstream microelectronic technology. Downsizing them led to the field of molecular spintronics. Here, we provide proof-of-concept data that allow expanding this area from its traditional focus on single-molecule magnets to molecules in which spin centers are antiferromagnetically (AFM) coupled to result in a singlet ground state. In this context, and in contrast to all previous work on molecular spintronics, we develop a detection scheme of the spin state of the molecule that does not rely on a magnetic moment. Instead, we use quantum dot devices consisting of an isolated, contacted single-wall carbon nanotube covalently bound to a limited number of molecular AFMs, for which we chose representative coordination complexes incorporating four Mn(II) or Co(II) ions. Time-dependent quantum transport measurements along the functionalized nanotube show steplike transitions between several distinct current levels that we attribute to transitions between different AFM states of individual molecular complexes grafted on the nanotube. A statistical analysis of the switching events using factorial cumulants indicates that the cobalt complexes switch independently from each other, whereas a coherent superposition of the AFM spin states of the molecules along the nanotube is observed for the manganese complexes. The long coherence time of the superposition state (several seconds at 100 mK) is made possible by the absence of spin and orbital momentum in the relevant states of the manganese complex, while the cobalt complex includes a significant orbital momentum contribution due to the pseudo-octahedral coordination environment of the d7 metal centers.

Original languageEnglish
Article number245414
Pages (from-to)1-10
Number of pages10
JournalPhysical Review B
Volume107
Issue number24
DOIs
Publication statusPublished - 15 Jun 2023

Bibliographical note

Publisher Copyright:
© 2023 American Physical Society.

Funding

The authors thank Christopher Nakamoto for helping with carrying out the synthesis and crystallization of the tetranuclear complexes and Christian Lurz for valuable discussions about the data analysis. We acknowledge financial support by the Deutsche Forschungsgemeinschaft under Project-ID No. 278162697-SFB 1242 as well as for individual Grants No. MA 4079/10-1, No. ME 3275/6-1, and No. ZA 780/3-1. P.S. acknowledges support from the German National Academy of Sciences Leopoldina (Grant No. LPDS 2019-10). Furthermore, Z.Z. acknowledges funding by the Ramón y Cajal programme RYC-2016-19344 (MINECO/AEI/FSE, UE), the Netherlands sectorplan program 2019–2023, and the research program “Materials for the Quantum Age” (QuMat, Registration No. 024.005.006), part of the Gravitation program of the Dutch Ministry of Education, Culture and Science (OCW). Z.Z., S.A., and N.W. acknowledge computer time from PRACE on Archer (EU Grant No. RI-653838) and on MareNostrum4 at Barcelona Supercomputing Center, Spain (OptoSpin Project ID No. 2020225411), from JARA-HPC (Project No. JHPC39), and from RES (Projects No. FI-2020-1-0014, No. FI-2020-1-0018, and No. FI-2020-2-0034) on MareNostrum4. Z.Z., S.A., N.W., and P.O. acknowledge the EC H2020-INFRAEDI-2018-2020 MaX Materials Design at the Exascale CoE (Grant No. 824143), Grant PGC2018-096955-B-C43 funded by Spain's MCIN / AEI / 10.13039/501100011033 and by ERDF - A way of making Europe, Spain's AEI Severo Ochoa Centers of Excellence Program (Grant No. SEV-2017-0706), and Generalitat de Catalunya CERCA programme (No. 2021 SGR 00997). N.W. acknowledges funding from the EU-H2020 research and innovation programme under the Marie Sklodowska-Curie programme (Grant No. 754558). This paper benefited from the access provided by ICN2 (Barcelona, Spain) within the framework of the NFFA-Europe Transnational Access Activity (Grant Agreement No. 654360, Proposal ID No. 753, submitted by C.M.). J.M. and A.V. acknowledge funding under ERC Grant No. 259286. C.M. acknowledges funding by Niedersächsisches Vorab Akz. 11-76251-14-3/15(ZN3141).

FundersFunder number
EC H2020-INFRAEDI-2018-2020PGC2018-096955-B-C43, MCIN / AEI / 10.13039/501100011033, 824143
EU-H2020 research and innovation programme
JARA-HPCFI-2020-1-0018, JHPC39, FI-2020-1-0014, FI-2020-2-0034
Marie Sklodowska-Curie programme654360, 754558
Niedersächsisches Vorab AkzZN3141, 11-76251-14-3/15
Ramón y CajalRYC-2016-19344
Faculty of Science and Engineering, University of Manchester024.005.006
Engineering Research Centers259286
Deutsche ForschungsgemeinschaftME 3275/6-1, 278162697-SFB 1242, ZA 780/3-1, MA 4079/10-1
Partnership for Advanced Computing in Europe AISBL2020225411, RI-653838
Generalitat de Catalunya2021 SGR 00997
Ministerie van onderwijs, cultuur en wetenschap
Ministerio de Economía y Competitividad
European Regional Development FundSEV-2017-0706
Deutsche Akademie der Naturforscher Leopoldina - Nationale Akademie der WissenschaftenLPDS 2019-10

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