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 language | English |
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Article number | 245414 |
Pages (from-to) | 1-10 |
Number of pages | 10 |
Journal | Physical Review B |
Volume | 107 |
Issue number | 24 |
DOIs | |
Publication status | Published - 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).
Funders | Funder number |
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EC H2020-INFRAEDI-2018-2020 | PGC2018-096955-B-C43, MCIN / AEI / 10.13039/501100011033, 824143 |
EU-H2020 research and innovation programme | |
JARA-HPC | FI-2020-1-0018, JHPC39, FI-2020-1-0014, FI-2020-2-0034 |
Marie Sklodowska-Curie programme | 654360, 754558 |
Niedersächsisches Vorab Akz | ZN3141, 11-76251-14-3/15 |
Ramón y Cajal | RYC-2016-19344 |
Faculty of Science and Engineering, University of Manchester | 024.005.006 |
Engineering Research Centers | 259286 |
Deutsche Forschungsgemeinschaft | ME 3275/6-1, 278162697-SFB 1242, ZA 780/3-1, MA 4079/10-1 |
Partnership for Advanced Computing in Europe AISBL | 2020225411, RI-653838 |
Generalitat de Catalunya | 2021 SGR 00997 |
Ministerie van onderwijs, cultuur en wetenschap | |
Ministerio de Economía y Competitividad | |
European Regional Development Fund | SEV-2017-0706 |
Deutsche Akademie der Naturforscher Leopoldina - Nationale Akademie der Wissenschaften | LPDS 2019-10 |