1
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Noei N, Mozara R, Montero AM, Brinker S, Ide N, Guimarães FSM, Lichtenstein AI, Berndt R, Lounis S, Weismann A. Manipulating the Spin Orientation of Co Atoms Using Monatomic Cu Chains. NANO LETTERS 2023; 23:8988-8994. [PMID: 37782684 DOI: 10.1021/acs.nanolett.3c02532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
Harnessing the spin of single atoms is at the heart of quantum information nanotechnology based on magnetic concepts. By attaching single Co atoms to monatomic Cu chains, we demonstrate the ability to control the spin orientation by the atomic environment. Due to spin-orbit coupling (SOC), the spin is tilted by ≈58° from the surface normal toward the chain as evidenced by inelastic tunneling spectroscopy. These findings are reproduced by density functional theory calculations and have implications for Co atoms on pristine Cu(111), which are believed to be Kondo systems. Our quantum Monte Carlo calculations suggest that SOC suppresses the Kondo effect of Co atoms at chains and on the flat surface. Our work impacts the fundamental understanding of low-energy excitations in nanostructures on surfaces and demonstrates the ability to manipulate atomic-scale magnetic moments, which can have tremendous implications for quantum devices.
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Affiliation(s)
- Neda Noei
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Roberto Mozara
- Institut für Theoretische Physik, Universität Hamburg, 20355 Hamburg, Germany
| | - Ana M Montero
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
| | - Sascha Brinker
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
| | - Niklas Ide
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Filipe S M Guimarães
- Jülich Supercomputing Centre, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany
| | | | - Richard Berndt
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Samir Lounis
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, 52425 Jülich, Germany
- Faculty of Physics, University of Duisburg-Essen and CENIDE, 47053 Duisburg, Germany
| | - Alexander Weismann
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
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2
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Wäckerlin C, Cahlík A, Goikoetxea J, Stetsovych O, Medvedeva D, Redondo J, Švec M, Delley B, Ondráček M, Pinar A, Blanco-Rey M, Kolorenč J, Arnau A, Jelínek P. Role of the Magnetic Anisotropy in Atomic-Spin Sensing of 1D Molecular Chains. ACS NANO 2022; 16:16402-16413. [PMID: 36200735 DOI: 10.1021/acsnano.2c05609] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
One-dimensional metal-organic chains often possess a complex magnetic structure susceptible to modification by alteration of their chemical composition. The possibility to tune their magnetic properties provides an interesting playground to explore quasi-particle interactions in low-dimensional systems. Despite the great effort invested so far, a detailed understanding of the interactions governing the electronic and magnetic properties of the low-dimensional systems is still incomplete. One of the reasons is the limited ability to characterize their magnetic properties at the atomic scale. Here, we provide a comprehensive study of the magnetic properties of metal-organic one-dimensional (1D) coordination polymers consisting of 2,5-diamino-1,4-benzoquinonediimine ligands coordinated with Co or Cr atoms synthesized under ultrahigh-vacuum conditions on a Au(111) surface. A combination of integral X-ray spectroscopy with local-probe inelastic electron tunneling spectroscopy corroborated by multiplet analysis, density functional theory, and inelastic electron tunneling simulations enables us to obtain essential information about their magnetic structures, including the spin magnitude and orientation at the magnetic atoms, as well as the magnetic anisotropy.
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Affiliation(s)
- Christian Wäckerlin
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 16200 Prague, Czech Republic
- Surface Science and Coating Technologies, Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland
| | - Aleš Cahlík
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 16200 Prague, Czech Republic
| | - Joseba Goikoetxea
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizábal 5, 20018 Donostia-San Sebastián, Spain
| | - Oleksandr Stetsovych
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 16200 Prague, Czech Republic
| | - Daria Medvedeva
- Institute of Physics, Czech Academy of Sciences, Na Slovance 2, 18221 Prague, Czech Republic
| | - Jesús Redondo
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 16200 Prague, Czech Republic
| | - Martin Švec
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 16200 Prague, Czech Republic
| | - Bernard Delley
- Condensed Matter Theory, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - Martin Ondráček
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 16200 Prague, Czech Republic
| | - Andres Pinar
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 16200 Prague, Czech Republic
- Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 12116 Prague, Czech Republic
| | - Maria Blanco-Rey
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Facultad de Química, UPV/EHU, Apartado 1072, 20080 Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizábal 4, 20018 Donostia-San Sebastián, Spain
| | - Jindřich Kolorenč
- Institute of Physics, Czech Academy of Sciences, Na Slovance 2, 18221 Prague, Czech Republic
| | - Andrés Arnau
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), Paseo Manuel de Lardizábal 5, 20018 Donostia-San Sebastián, Spain
- Departamento de Polímeros y Materiales Avanzados: Física, Química y Tecnología, Facultad de Química, UPV/EHU, Apartado 1072, 20080 Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizábal 4, 20018 Donostia-San Sebastián, Spain
| | - Pavel Jelínek
- Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, 16200 Prague, Czech Republic
- Donostia International Physics Center (DIPC), Paseo Manuel de Lardizábal 4, 20018 Donostia-San Sebastián, Spain
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3
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She L, Shen Z, Xie Z, Wang L, Song Y, Wang XS, Jia Y, Zhang Z, Zhang W. Magnetic Moment Preservation and Emergent Kondo Resonance of Co-Phthalocyanine on Semimetallic Sb(111). PHYSICAL REVIEW LETTERS 2022; 129:026802. [PMID: 35867437 DOI: 10.1103/physrevlett.129.026802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 03/28/2022] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
Abstract
Magnetic molecules on surfaces have been widely investigated to reveal delicate interfacial couplings and for potential technological applications. In these endeavors, one prevailing challenge is how to preserve or recover the molecular spins, especially on highly metallic substrates that can readily quench the magnetic moments of the admolecules. Here, we use scanning tunneling microscopy and spectroscopy to exploit the semimetallic nature of antimony and observe, surprisingly yet pleasantly, that the spin of Co-phthalocyanine is well preserved on Sb(111), as unambiguously evidenced by the emergent strong Kondo resonance across the molecule. Our first-principles calculations further confirm that the optimal density of states near the Fermi level of the semimetal is a decisive factor, weakening the overall interfacial coupling, while still ensuring sufficiently effective electron-spin scattering in the many-body system. Beyond isolated admolecules, we discover that each of the magnetic moments in a molecular dimer or a densely packed island is distinctly preserved as well, rendering such molecular magnets immense potentials for ultrahigh density memory devices.
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Affiliation(s)
- Limin She
- Key Laboratory for Quantum Matters, and Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng 475004, China
| | - Zhitao Shen
- Key Laboratory for Quantum Matters, and Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng 475004, China
| | - Zhenyang Xie
- Key Laboratory for Quantum Matters, and Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng 475004, China
| | - Limei Wang
- Key Laboratory for Quantum Matters, and Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng 475004, China
| | - Yeheng Song
- Key Laboratory for Quantum Matters, and Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng 475004, China
| | - Xue-Sen Wang
- Key Laboratory for Quantum Matters, and Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng 475004, China
- Department of Physics, National University of Singapore, 117542, Singapore
| | - Yu Jia
- Key Laboratory for Quantum Matters, and Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng 475004, China
- International Laboratory for Quantum Functional Materials of Henan, Zhengzhou University, Zhengzhou 450003, China
- Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004, China
| | - Zhenyu Zhang
- International Center for Quantum Design of Functional Materials (ICQD), University of Science and Technology of China, Hefei 230026, China
| | - Weifeng Zhang
- Key Laboratory for Quantum Matters, and Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng 475004, China
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4
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Flores F, Tacca M, Goldberg E. An ionic Hamiltonian for transition metal atoms: Kondo resonances and tunneling currents. ADVANCES IN QUANTUM CHEMISTRY 2022. [DOI: 10.1016/bs.aiq.2022.05.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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5
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Veldman LM, Farinacci L, Rejali R, Broekhoven R, Gobeil J, Coffey D, Ternes M, Otte AF. Free coherent evolution of a coupled atomic spin system initialized by electron scattering. Science 2021; 372:964-968. [PMID: 34045351 DOI: 10.1126/science.abg8223] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 02/19/2021] [Accepted: 04/23/2021] [Indexed: 11/02/2022]
Abstract
Full insight into the dynamics of a coupled quantum system depends on the ability to follow the effect of a local excitation in real-time. Here, we trace the free coherent evolution of a pair of coupled atomic spins by means of scanning tunneling microscopy. Rather than using microwave pulses, we use a direct-current pump-probe scheme to detect the local magnetization after a current-induced excitation performed on one of the spins. By making use of magnetic interaction with the probe tip, we are able to tune the relative precession of the spins. We show that only if their Larmor frequencies match, the two spins can entangle, causing angular momentum to be swapped back and forth. These results provide insight into the locality of electron spin scattering and set the stage for controlled migration of a quantum state through an extended spin lattice.
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Affiliation(s)
- Lukas M Veldman
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, the Netherlands
| | - Laëtitia Farinacci
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, the Netherlands
| | - Rasa Rejali
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, the Netherlands
| | - Rik Broekhoven
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, the Netherlands
| | - Jérémie Gobeil
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, the Netherlands
| | - David Coffey
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, the Netherlands
| | - Markus Ternes
- RWTH Aachen University, Institute of Physics, D-52074 Aachen, Germany.,Peter-Grünberg-Institute, Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Alexander F Otte
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2628 CJ Delft, the Netherlands.
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6
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Garnier L, Verlhac B, Abufager P, Lorente N, Ormaza M, Limot L. The Kondo Effect of a Molecular Tip As a Magnetic Sensor. NANO LETTERS 2020; 20:8193-8199. [PMID: 33119321 DOI: 10.1021/acs.nanolett.0c03271] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A single molecule offers to tailor and control the probing capability of a scanning tunneling microscope when placed on the tip. With the help of first-principles calculations, we show that on-tip spin sensitivity is possible through the Kondo ground state of a spin S = 1/2 cobaltocene molecule. When attached to the tip apex, we observe a reproducible Kondo resonance, which splits apart upon tuning the exchange coupling of cobaltocene to an iron atom on the surface. The spin-split Kondo resonance provides quantitative information on the exchange field and on the spin polarization of the iron atom. We also demonstrate that molecular vibrations cause the emergence of Kondo side peaks, which, unlike the Kondo resonance, are sensitive to cobaltocene adsorption.
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Affiliation(s)
- Léo Garnier
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg F-67000, France
| | - Benjamin Verlhac
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg F-67000, France
| | - Paula Abufager
- Instituto de Física de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Universidad Nacional de Rosario, Avenida Pellegrini 250 (2000), Rosario 2000, Argentina
| | - Nicolás Lorente
- Centro de Física de Materiales (CFM), Donostia-San San Sebastián20018, Spain
- Donostia International Physics Center (DIPC), Donostia-San Sebastián20018, Spain
| | - Maider Ormaza
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg F-67000, France
| | - Laurent Limot
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, Strasbourg F-67000, France
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7
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Enhanced magnetic spin-spin interactions observed between porphyrazine derivatives on Au(111). Commun Chem 2020; 3:36. [PMID: 36703412 PMCID: PMC9814269 DOI: 10.1038/s42004-020-0282-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 02/28/2020] [Indexed: 01/29/2023] Open
Abstract
Magnetic molecules are of interest for application in spintronic and quantum-information processing devices. Therein, control of the interaction between the spins of neighboring molecules is the critical issue. Substitution of outer moieties of the molecule can tune the molecule-molecule interaction. Here we show a novel spin behavior for a magnetic molecule of vanadyl tetrakis (thiadiazole) porphyrazine (abbreviated as VOTTDPz) adsorbed on Au(111), which is modified from vanadyl phthalocyanine (VOPc) by replacing the inert phthalocyanine ligand with a reactive thiadiazole moiety. The magnetic properties of the molecules are examined by observing the Kondo resonance caused by the screening of an isolated spin by conduction electrons using scanning tunneling spectroscopy. The Kondo features are detected at the molecule whose shape and intensity show site-dependent variation, revealing complex spin-spin interactions due to the enhanced interaction between molecules, originating from the functionalization of the ligand with a more reactive moiety.
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8
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Néel N, Shao B, Wehling TO, Kröger J. Manipulation of the two-site Kondo effect in linear CoCu n CoCu m clusters. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:055303. [PMID: 31604345 DOI: 10.1088/1361-648x/ab4d17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Artificially assembled linear atomic clusters, CoCu n CoCu m , are used to explore variations of the Kondo effect at the two Co sites. For all investigated Cu n chain lengths ([Formula: see text]) the addition of a single Cu atom to one edge Co atom of the chain ([Formula: see text]) strongly reduces the amplitude of the Abrikosov-Suhl-Kondo resonance of that Co atom. Concomitantly, the resonance line width is more than halved. On the contrary, the Kondo effect of the opposite edge Co atom remains unaffected. Hybridization together with the linear geometry of the cluster are likely to drive the effect.
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Affiliation(s)
- N Néel
- Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany
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9
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Kozanecki M, Rudowicz C. Importance of the fourth-rank zero field splitting parameters for Fe 2+ ( S = 2) adatoms on the CuN/Cu(100) surface evidenced by their determination based on DFT and experimental data. Phys Chem Chem Phys 2020; 22:19837-19844. [DOI: 10.1039/d0cp02986f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Equations allow to determine 2nd- and 4th-rank ZFSPs (Bkq) based on spin energy levels (λi) at B = 0. This method is applied to Fe2+ (S = 2) adatoms on CuN/Cu(100) surface using DFT and experimental data. Relative importance of ZFSPs is analyzed.
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Affiliation(s)
- Michał Kozanecki
- Faculty of Chemistry
- Adam Mickiewicz University
- 61-614 Poznań
- Poland
| | - Czesław Rudowicz
- Faculty of Chemistry
- Adam Mickiewicz University
- 61-614 Poznań
- Poland
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10
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Wang Y, Li X, Yang J. Spin-flip excitations induced by dehydrogenation in a magnetic single-molecule junction. J Chem Phys 2019; 151:224704. [DOI: 10.1063/1.5129288] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Yu Wang
- Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Xiaoguang Li
- Institute for Advanced Study, Shenzhen University, Shenzhen 518060, China
| | - Jinlong Yang
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
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11
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Verlhac B, Bachellier N, Garnier L, Ormaza M, Abufager P, Robles R, Bocquet ML, Ternes M, Lorente N, Limot L. Atomic-scale spin sensing with a single molecule at the apex of a scanning tunneling microscope. Science 2019; 366:623-627. [DOI: 10.1126/science.aax8222] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 10/08/2019] [Indexed: 11/03/2022]
Affiliation(s)
- B. Verlhac
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - N. Bachellier
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - L. Garnier
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - M. Ormaza
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
| | - P. Abufager
- Instituto de Física de Rosario, CONICET and Universidad Nacional de Rosario, Av. Pellegrini 250 (2000) Rosario, Argentina
| | - R. Robles
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastián, Spain
| | - M.-L. Bocquet
- PASTEUR, Département de Chimie, Ecole Normale Supérieure, PSL Research University, Sorbonne Universités, UPMC Univ. Paris 06, CNRS, 75005 Paris, France
| | - M. Ternes
- Institute of Physics II B, RWTH Aachen University, 52074 Aachen, Germany
- Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - N. Lorente
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastián, Spain
| | - L. Limot
- Université de Strasbourg, CNRS, IPCMS, UMR 7504, F-67000 Strasbourg, France
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12
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Moro-Lagares M, Korytár R, Piantek M, Robles R, Lorente N, Pascual JI, Ibarra MR, Serrate D. Real space manifestations of coherent screening in atomic scale Kondo lattices. Nat Commun 2019; 10:2211. [PMID: 31101815 PMCID: PMC6525169 DOI: 10.1038/s41467-019-10103-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/18/2019] [Indexed: 11/10/2022] Open
Abstract
The interaction among magnetic moments screened by conduction electrons drives quantum phase transitions between magnetically ordered and heavy-fermion ground states. Here, starting from isolated magnetic impurities in the Kondo regime, we investigate the formation of the finite size analogue of a heavy Fermi liquid. We build regularly-spaced chains of Co adatoms on a metallic surface by atomic manipulation. Scanning tunneling spectroscopy is used to obtain maps of the Kondo resonance intensity with sub-atomic resolution. For sufficiently small interatomic separation, the spatial distribution of Kondo screening does not coincide with the position of the adatoms. It also develops enhancements at both edges of the chains. Since we can rule out any other interaction between Kondo impurities, this is explained in terms of the indirect hybridization of the Kondo orbitals mediated by a coherent electron gas, the mechanism that causes the emergence of heavy quasiparticles in the thermodynamic limit.
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Affiliation(s)
- María Moro-Lagares
- Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragón, University of Zaragoza, E-50018, Zaragoza, Spain.,Institute of Physics, Academy of Sciences, Prague, 16200, Czech Republic.,Regional Centre of Advanced Technologies and Materials, Faculty of Science, Department of Physical Chemistry, Palacky University, Olomouc, 78371, Czech Republic
| | - Richard Korytár
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, 121 16, Prague 2, Czech Republic
| | - Marten Piantek
- Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragón, University of Zaragoza, E-50018, Zaragoza, Spain.,Dpto.Física Materia Condensada, University of Zaragoza, E-50009, Zaragoza, Spain
| | - Roberto Robles
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, Bellaterra, 08193, Barcelona, Spain
| | - Nicolás Lorente
- Centro de Física de Materiales CFM/MPC (CSIC-UPV/EHU), 20018, Donostia-San Sebastián, Spain.,Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastian, Spain
| | - Jose I Pascual
- Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragón, University of Zaragoza, E-50018, Zaragoza, Spain.,CIC NanoGUNE, E-20018, Donostia-San Sebastián, Spain.,IKERBASQUE, Basque Foundation for Science, E-48011, Bilbao, Spain
| | - M Ricardo Ibarra
- Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragón, University of Zaragoza, E-50018, Zaragoza, Spain.,Dpto.Física Materia Condensada, University of Zaragoza, E-50009, Zaragoza, Spain
| | - David Serrate
- Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragón, University of Zaragoza, E-50018, Zaragoza, Spain. .,Dpto.Física Materia Condensada, University of Zaragoza, E-50009, Zaragoza, Spain. .,Instituto de Ciencia de Materiales de Aragón, CSIC - Universidad de Zaragoza, 50009, Zaragoza, Spain.
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13
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Inelastic electron excitation of transition metal atoms and Kondo resonances. ADVANCES IN QUANTUM CHEMISTRY 2019. [DOI: 10.1016/bs.aiq.2019.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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14
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Ibañez-Azpiroz J, Dos Santos Dias M, Blügel S, Lounis S. Spin-fluctuation and spin-relaxation effects of single adatoms from first principles. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:343002. [PMID: 30020083 DOI: 10.1088/1361-648x/aad43d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Single adatoms offer an exceptional playground for studying magnetism and its associated dynamics at the atomic scale. Here we review recent results on single adatoms deposited on metallic substrates, based on time-dependent density functional theory. First we analyze quantum zero-point spin-fluctuations (ZPSF) as calculated from the fluctuation-dissipation theorem, and show how they affect the magnetic stability by modifying the magnetic anisotropy energy. We also assess the impact of ZPSF in the limit of small hybridization to the substrate characteristic of semi-insulating substrates, connecting to recent experimental investigations where magnetic stability of a single adatom was achieved for the first time. Secondly, we inspect further the dynamics of single adatoms by considering the longitudinal and transverse spin-relaxation processes, whose time-scales are analyzed and related to the underlying electronic structure of both the adatom and the substrate. Thirdly, we analyze spin-fluctuation modes of paramagnetic adatoms, i.e. adatoms where the Stoner criterion for magnetism is almost fulfilled. Interestingly, such modes can develop well-defined peaks in the meV range, their main characteristics being determined by two fundamental electronic properties, namely the Stoner parameter and the density of states at the Fermi level. Furthermore, simulated inelastic scanning tunneling spectroscopy curves reveal that these spin-fluctuation modes can be triggered by tunneling electrons, opening up potential applications also for paramagnetic adatoms. Lastly, an overview of the outstanding issues and future directions is given.
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Affiliation(s)
- Julen Ibañez-Azpiroz
- Centro de Física de Materiales, Universidad del País Vasco, 20018 San Sebastián, Spain
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15
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Granet J, Sicot M, Kierren B, Lamare S, Chérioux F, Baudelet F, Fagot-Revurat Y, Moreau L, Malterre D. Tuning the Kondo resonance in two-dimensional lattices of cerium molecular complexes. NANOSCALE 2018; 10:9123-9132. [PMID: 29721558 DOI: 10.1039/c7nr08202a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Cerium intermetallics have raised a lot of interest for the past forty years thanks to their very unusual and interesting electronic and magnetic properties. This can be explained by the peculiar electronic configuration of Ce (4f1) that allows different oxidation states leading to singular behavior such as quantum phase transitions, heavy-fermion behavior and the Kondo effect. In this work, we used a mixed-valence molecular analogue to study the Kondo effect down to the atomic scale by means of scanning tunneling microscopy/spectroscopy (STM/STS) for which new many-body effects are expected to emerge due to reduced dimensionality and specific chemical environment of the 4f-ion. For that purpose, double-decker molecular complexes hosting a Ce ion were synthesized and adsorbed onto Ag and Cu (111) surfaces forming two-dimensional lattices. As a result, we observed a zero-bias conductance resonance on Ag only indicative of a Kondo effect arising from the coupling between a molecular spin and the conducting electrons of the metallic surface. The emergence of the Kondo effect is discussed in terms of intermolecular and molecule/substrate interactions. This work expands the little knowledge to date on the structural and related electronic properties of Ce-based molecular systems on surfaces. In particular, it shows that Ce-based double deckers are good platforms to obtain insight into 4f-induced many-body effects down to the nanometer scale and in two-dimensional lattices. Moreover, this outcome has a strong impact for future applications of molecular devices in which both metals are commonly used as electrical contacts.
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Affiliation(s)
- Julien Granet
- Institut Jean Lamour, UMR 7198, CNRS-Université de Lorraine, Campus ARTEM, 2 allée André Guinier, BP 50840, 54011 Nancy, France.
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16
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Huang Z, Zhang Y, He Y, Song H, Yin C, Wu K. A chemist's overview of surface electron spins. Chem Soc Rev 2018; 46:1955-1976. [PMID: 28317957 DOI: 10.1039/c6cs00891g] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
This review summarizes recent research progress in the measurement and tuning of the electron spins of alien atoms and molecules adsorbed on well-defined substrates. After a brief introduction to the main experimental techniques employed to study surface electron spins, some well-explored systems consisting of atomic and molecular spin-carriers at surfaces are overviewed from a chemist's viewpoint, focusing on the experimental measurements and chemical modifications of the electron spin states of the alien entities at the surfaces on the atomic/molecular level. Finally, personal perspectives have been provided, aiming at describing some of the remaining issues that need to be addressed in the future and proposing potential applications in surface chemistry.
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Affiliation(s)
- Zhichao Huang
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| | - Yajie Zhang
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| | - Yang He
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| | - Huanjun Song
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| | - Cen Yin
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
| | - Kai Wu
- BNLMS, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
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17
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Wang Y, Li X, Zheng X, Yang J. Manipulation of spin and magnetic anisotropy in bilayer magnetic molecular junctions. Phys Chem Chem Phys 2018; 20:26396-26404. [DOI: 10.1039/c8cp05759a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The Kondo effect and magnetic anisotropy in bilayer TMPc/TMPc/Pb(111) junctions can be actively tuned by changing the intermediate decoupling layer.
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Affiliation(s)
- Yu Wang
- Institute for Advanced Study
- Shenzhen University
- Shenzhen 518060
- China
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province
| | - Xiaoguang Li
- Institute for Advanced Study
- Shenzhen University
- Shenzhen 518060
- China
| | - Xiao Zheng
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics
- University of Science and Technology of China
- Hefei 230026
- China
| | - Jinlong Yang
- Hefei National Laboratory for Physical Sciences at the Microscale and Synergetic Innovation Center of Quantum Information and Quantum Physics
- University of Science and Technology of China
- Hefei 230026
- China
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18
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Choi DJ, Robles R, Yan S, Burgess JAJ, Rolf-Pissarczyk S, Gauyacq JP, Lorente N, Ternes M, Loth S. Building Complex Kondo Impurities by Manipulating Entangled Spin Chains. NANO LETTERS 2017; 17:6203-6209. [PMID: 28872317 DOI: 10.1021/acs.nanolett.7b02882] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The creation of molecule-like structures in which magnetic atoms interact controllably is full of potential for the study of complex or strongly correlated systems. Here, we create spin chains in which a strongly correlated Kondo state emerges from magnetic coupling of transition-metal atoms. We build chains up to ten atoms in length by placing Fe and Mn atoms on a Cu2N surface with a scanning tunneling microscope. The atoms couple antiferromagnetically via superexchange interaction through the nitrogen atom network of the surface. The emergent Kondo resonance is spatially distributed along the chain. Its strength can be controlled by mixing atoms of different transition metal elements and manipulating their spatial distribution. We show that the Kondo screening of the full chain by the electrons of the nonmagnetic substrate depends on the interatomic entanglement of the spins in the chain, demonstrating the prerequisites to build and probe spatially extended strongly correlated nanostructures.
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Affiliation(s)
- Deung-Jang Choi
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany
- Max Planck Institute for Solid State Research , Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Roberto Robles
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology , Campus UAB, Bellaterra, 08193 Barcelona, Spain
| | - Shichao Yan
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany
- Max Planck Institute for Solid State Research , Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Jacob A J Burgess
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany
- Max Planck Institute for Solid State Research , Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Steffen Rolf-Pissarczyk
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany
- Max Planck Institute for Solid State Research , Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Jean-Pierre Gauyacq
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay , Bât. 351, 91405 Orsay Cedex, France
| | - Nicolás Lorente
- Centro de Física de Materiales, CFM/MPC (CSIC-UPV/EHU) , Paseo Manuel de Lardizabal 5, 20018 Donostia-San Sebastián, Spain
- Donostia International Physics Center (DIPC) , Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastián, Spain
| | - Markus Ternes
- Max Planck Institute for Solid State Research , Heisenbergstr. 1, 70569 Stuttgart, Germany
| | - Sebastian Loth
- Max Planck Institute for the Structure and Dynamics of Matter , Luruper Chaussee 149, 22761 Hamburg, Germany
- Max Planck Institute for Solid State Research , Heisenbergstr. 1, 70569 Stuttgart, Germany
- Institute for Functional Matter and Quantum Technologies, University of Stuttgart , Pfaffenwaldring 57, 70569 Stuttgart, Germany
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19
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Switching of spins and entanglement in surface-supported antiferromagnetic chains. Sci Rep 2017; 7:2759. [PMID: 28584280 PMCID: PMC5459826 DOI: 10.1038/s41598-017-02972-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 04/20/2017] [Indexed: 11/08/2022] Open
Abstract
Previous experimental studies discovered universal growth of chains and nanowires of various chemical elements on a corrugated molecular network of Cu3N on the Cu(110). Herein, performing combined ab initio and quantum Hamiltonian studies we demonstrate that such chains can be used for a fast spin switching and entanglement generation by locally applied magnetic pulses. As an example, we show that in antiferromagnetic Co chains a strong entanglement between ends of chains occurs during spin switching. A novel parity effect in spin dynamics is reported. Even-numbered chains are found to exhibit significantly faster spin switching than odd-numbered counterparts. Moreover, at certain parameters of the system the dimerization effect in the spin dynamics of the chains was found. Our studies give a clear evidence that tailoring spin dynamics and entanglement can be achieved by magnetic fields and by tuning exchange interactions in supported chains.
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20
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The geometric phase of Z n- and T-symmetric nanomagnets as a classification toolkit. Sci Rep 2017; 7:46614. [PMID: 28440279 PMCID: PMC5404233 DOI: 10.1038/srep46614] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 03/21/2017] [Indexed: 11/08/2022] Open
Abstract
We derive the general form of the non-trivial geometric phase resulting from the unique combination of point group and time reversal symmetries. This phase arises e.g. when a magnetic adatom is adsorbed on a non-magnetic Cn crystal surface, where n denotes the fold of the principal axis. The energetic ordering and the relevant quantum numbers of the eigenstates are entirely determined by this quantity. Moreover, this phase allows to conveniently predict the protection mechanism of any prepared state, shedding light onto a large number of experiments and allowing a classification scheme. Owing to its robustness this geometric phase also has great relevance for a large number of applications in quantum computing, where topologically protected states bearing long relaxation times are highly desired.
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21
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Flores F, Goldberg EC. Ionic Hamiltonians for transition metal atoms: effective exchange coupling and Kondo temperature. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:055602. [PMID: 27966475 DOI: 10.1088/1361-648x/aa4dda] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An ionic Hamiltonian for describing the interaction between a metal and a d-shell transition metal atom having an orbital singlet state is introduced and its properties analyzed using the Schrieffer-Wolf transformation (exchange coupling) and the poor man's scaling method (Kondo temperature). We find that the effective exchange coupling between the metal and the atom has an antiferromagnetic or a ferromagnetic interaction depending on the kind of atomic fluctuations, either [Formula: see text] or [Formula: see text], associated with the metal-atom coupling. We present a general scheme for all those processes and calculate, for the antiferromagnetic interaction, the corresponding Kondo-temperature.
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Affiliation(s)
- F Flores
- Departamento de Física Teórica de la Materia Condensada and IFIMAC, Cantoblanco, Universidad Autónoma, E-28049, Madrid, Spain
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22
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Choi DJ, Guissart S, Ormaza M, Bachellier N, Bengone O, Simon P, Limot L. Kondo Resonance of a Co Atom Exchange Coupled to a Ferromagnetic Tip. NANO LETTERS 2016; 16:6298-6302. [PMID: 27598512 DOI: 10.1021/acs.nanolett.6b02617] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The Kondo effect of a Co atom on Cu(100) was investigated with a low-temperature scanning tunneling microscope using a monoatomically sharp nickel tip. Upon a tip-Co contact, the differential conductance spectra exhibit a spin-split asymmetric Kondo resonance. The computed ab initio value of the exchange coupling is too small to suppress the Kondo effect, but sufficiently large to produce the splitting observed. A quantitative analysis of the line shape using the numerical renormalization group technique indicates that the junction spin polarization is weak.
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Affiliation(s)
- D-J Choi
- IPCMS, CNRS UMR 7504, Université de Strasbourg , 67034 Strasbourg, France
- CIC nanoGUNE , 20018 Donostia-San Sebastián, Spain
| | - S Guissart
- Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris-Sud 11 , 91405 Orsay, France
| | - M Ormaza
- IPCMS, CNRS UMR 7504, Université de Strasbourg , 67034 Strasbourg, France
| | - N Bachellier
- IPCMS, CNRS UMR 7504, Université de Strasbourg , 67034 Strasbourg, France
| | - O Bengone
- IPCMS, CNRS UMR 7504, Université de Strasbourg , 67034 Strasbourg, France
| | - P Simon
- Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris-Sud 11 , 91405 Orsay, France
| | - L Limot
- IPCMS, CNRS UMR 7504, Université de Strasbourg , 67034 Strasbourg, France
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23
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Khajetoorians AA, Steinbrecher M, Ternes M, Bouhassoune M, dos Santos Dias M, Lounis S, Wiebe J, Wiesendanger R. Tailoring the chiral magnetic interaction between two individual atoms. Nat Commun 2016; 7:10620. [PMID: 26902332 PMCID: PMC4766390 DOI: 10.1038/ncomms10620] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 01/05/2016] [Indexed: 11/13/2022] Open
Abstract
Chiral magnets are a promising route towards dense magnetic storage technology due to their inherent nano-scale dimensions and energy efficient properties. Engineering chiral magnets requires atomic-level control of the magnetic exchange interactions, including the Dzyaloshinskii–Moriya interaction, which defines a rotational sense for the magnetization of two coupled magnetic moments. Here we show that the indirect conduction electron-mediated Dzyaloshinskii–Moriya interaction between two individual magnetic atoms on a metallic surface can be manipulated by changing the interatomic distance with the tip of a scanning tunnelling microscope. We quantify this interaction by comparing our measurements to a quantum magnetic model and ab-initio calculations yielding a map of the chiral ground states of pairs of atoms depending on the interatomic separation. The map enables tailoring the chirality of the magnetization in dilute atomic-scale magnets. The Dzyaloshinskii-Moriya exchange interaction arises in magnetic systems with broken inversion symmetry and promotes chiral magnetic order which may be exploited in spintronic devices. Here, the authors demonstrate how such an interaction between magnetic atoms on a metallic surface may be tuned by their separation.
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Affiliation(s)
- A A Khajetoorians
- Department of Physics, Hamburg University, 20355 Hamburg, Germany.,Institute for Molecules and Materials, Radboud University, 6525AJ Nijmegen, The Netherlands
| | - M Steinbrecher
- Department of Physics, Hamburg University, 20355 Hamburg, Germany
| | - M Ternes
- Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - M Bouhassoune
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich &JARA, 52425 Jülich, Germany
| | - M dos Santos Dias
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich &JARA, 52425 Jülich, Germany
| | - S Lounis
- Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich &JARA, 52425 Jülich, Germany
| | - J Wiebe
- Department of Physics, Hamburg University, 20355 Hamburg, Germany
| | - R Wiesendanger
- Department of Physics, Hamburg University, 20355 Hamburg, Germany
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24
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Absence of a spin-signature from a single Ho adatom as probed by spin-sensitive tunneling. Nat Commun 2016; 7:10454. [PMID: 26838811 PMCID: PMC4742789 DOI: 10.1038/ncomms10454] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 12/10/2015] [Indexed: 11/08/2022] Open
Abstract
Whether rare-earth materials can be used as single-atom magnetic memory is an ongoing debate in recent literature. Here we show, by inelastic and spin-resolved scanning tunnelling-based methods, that we observe a strong magnetic signal and excitation from Fe atoms adsorbed on Pt(111), but see no signatures of magnetic excitation or spin-based telegraph noise for Ho atoms. Moreover, we observe that the indirect exchange field produced by a single Ho atom is negligible, as sensed by nearby Fe atoms. We demonstrate, using ab initio methods, that this stems from a comparatively weak coupling of the Ho 4f electrons with both tunnelling electrons and substrate-derived itinerant electrons, making both magnetic coupling and detection very difficult when compared to 3d elements. We discuss these results in the context of ongoing disputes and clarify important controversies. Magnetic stability of holmium atoms on a platinum(111) surface has recently been reported, raising prospects for atomic-scale spintronics, however contradictory results have since emerged. Here, Steinbrecher et al. find evidence for an invisibility of the holmium spin to scanning tunnelling spectroscopy techniques which challenges recent results.
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25
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Exploring the phase diagram of the two-impurity Kondo problem. Nat Commun 2015; 6:10046. [PMID: 26616044 PMCID: PMC4674668 DOI: 10.1038/ncomms10046] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 10/29/2015] [Indexed: 12/04/2022] Open
Abstract
A system of two exchange-coupled Kondo impurities in a magnetic field gives rise to a rich phase space hosting a multitude of correlated phenomena. Magnetic atoms on surfaces probed through scanning tunnelling microscopy provide an excellent platform to investigate coupled impurities, but typical high Kondo temperatures prevent field-dependent studies from being performed, rendering large parts of the phase space inaccessible. We present a study of pairs of Co atoms on insulating Cu2N/Cu(100), which each have a Kondo temperature of only 2.6 K. The pairs are designed to have interaction strengths similar to the Kondo temperature. By applying a sufficiently strong magnetic field, we are able to access a new phase in which the two coupled impurities are simultaneously screened. Comparison of differential conductance spectra taken on the atoms to simulated curves, calculated using a third-order transport model, allows us to independently determine the degree of Kondo screening in each phase. Magnetic atoms on a surface possess diverse correlated phases under an applied magnetic field due to a balance of exchange interaction and carrier-mediated coupling. Here, the authors use scanning tunnel microscopy to explore the phase diagram of coupled Co atom pairs on the surface of Cu2N/Cu(100).
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26
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Bryant B, Toskovic R, Ferrón A, Lado JL, Spinelli A, Fernández-Rossier J, Otte AF. Controlled Complete Suppression of Single-Atom Inelastic Spin and Orbital Cotunneling. NANO LETTERS 2015; 15:6542-6546. [PMID: 26366713 DOI: 10.1021/acs.nanolett.5b02200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The inelastic portion of the tunnel current through an individual magnetic atom grants unique access to read out and change the atom's spin state, but it also provides a path for spontaneous relaxation and decoherence. Controlled closure of the inelastic channel would allow for the latter to be switched off at will, paving the way to coherent spin manipulation in single atoms. Here, we demonstrate complete closure of the inelastic channels for both spin and orbital transitions due to a controlled geometric modification of the atom's environment, using scanning tunneling microscopy (STM). The observed suppression of the excitation signal, which occurs for Co atoms assembled into chains on a Cu2N substrate, indicates a structural transition affecting the dz(2) orbital, effectively cutting off the STM tip from the spin-flip cotunneling path.
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Affiliation(s)
- Benjamin Bryant
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology , Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Ranko Toskovic
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology , Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Alejandro Ferrón
- International Iberian Nanotechnology Laboratory (INL) , Avenida Mestre José Veiga, 4715-330 Braga, Portugal
- Instituto de Modelado e Innovación Tecnológica (CONICET-UNNE) , Avenida Libertad 5400, W3404AAS Corrientes, Argentina
| | - José L Lado
- International Iberian Nanotechnology Laboratory (INL) , Avenida Mestre José Veiga, 4715-330 Braga, Portugal
| | - Anna Spinelli
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology , Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - Joaquín Fernández-Rossier
- International Iberian Nanotechnology Laboratory (INL) , Avenida Mestre José Veiga, 4715-330 Braga, Portugal
- Departamento de Fı́sica Aplicada, Universidad de Alicante , San Vicente del Raspeig, 03690, Spain
| | - Alexander F Otte
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology , Lorentzweg 1, 2628 CJ Delft, The Netherlands
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27
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Coffey D, Diez-Ferrer JL, Serrate D, Ciria M, Fuente CDL, Arnaudas JI. Antiferromagnetic Spin Coupling between Rare Earth Adatoms and Iron Islands Probed by Spin-Polarized Tunneling. Sci Rep 2015; 5:13709. [PMID: 26333417 PMCID: PMC4558548 DOI: 10.1038/srep13709] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 08/03/2015] [Indexed: 11/16/2022] Open
Abstract
High-density magnetic storage or quantum computing could be achieved using small magnets with large magnetic anisotropy, a requirement that rare-earth iron alloys fulfill in bulk. This compelling property demands a thorough investigation of the magnetism in low dimensional rare-earth iron structures. Here, we report on the magnetic coupling between 4f single atoms and a 3d magnetic nanoisland. Thulium and lutetium adatoms deposited on iron monolayer islands pseudomorphically grown on W(110) have been investigated at low temperature with scanning tunneling microscopy and spectroscopy. The spin-polarized current indicates that both kind of adatoms have in-plane magnetic moments, which couple antiferromagnetically with their underlying iron islands. Our first-principles calculations explain the observed behavior, predicting an antiparallel coupling of the induced 5d electrons magnetic moment of the lanthanides with the 3d magnetic moment of iron, as well as their in-plane orientation, and pointing to a non-contribution of 4f electrons to the spin-polarized tunneling processes in rare earths.
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Affiliation(s)
- David Coffey
- Laboratorio de Microscopías Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza, Spain
- Instituto de Ciencia de Materiales de Aragón, Consejo Superior de Investigaciones Científicas, Zaragoza, Spain
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, Spain
| | - José Luis Diez-Ferrer
- Laboratorio de Microscopías Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza, Spain
| | - David Serrate
- Laboratorio de Microscopías Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza, Spain
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, Spain
| | - Miguel Ciria
- Instituto de Ciencia de Materiales de Aragón, Consejo Superior de Investigaciones Científicas, Zaragoza, Spain
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, Spain
| | - César de la Fuente
- Instituto de Ciencia de Materiales de Aragón, Consejo Superior de Investigaciones Científicas, Zaragoza, Spain
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, Spain
| | - José Ignacio Arnaudas
- Laboratorio de Microscopías Avanzadas, Instituto de Nanociencia de Aragón, Universidad de Zaragoza, Zaragoza, Spain
- Departamento de Física de la Materia Condensada, Universidad de Zaragoza, Zaragoza, Spain
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28
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Spinelli A, Rebergen MP, Otte AAF. Atomically crafted spin lattices as model systems for quantum magnetism. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2015; 27:243203. [PMID: 26034814 DOI: 10.1088/0953-8984/27/24/243203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Low-dimensional quantum magnetism presents a seemingly unlimited source of rich, intriguing physics. Yet, because realistic experimental representations are difficult to come by, the field remains predominantly theoretical. In recent years, artificial spin structures built through manipulation of magnetic atoms in a scanning tunnelling microscope have developed into a promising testing ground for experimental verification of theoretical models. Here, we present an overview of available tools and discuss recent achievements as well as future avenues. Moreover, we show new observations on magnetic switching in a bistable bit that can be used to extrapolate information on the magnetisation of the microscope tip.
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Affiliation(s)
- A Spinelli
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, the Netherlands
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29
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Li Z, Chen HYT, Schouteden K, Janssens E, Van Haesendonck C, Lievens P, Pacchioni G. Spontaneous doping of two-dimensional NaCl films with Cr atoms: aggregation and electronic structure. NANOSCALE 2015; 7:2366-2373. [PMID: 25563389 DOI: 10.1039/c4nr07003h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Scanning tunneling microscopy (STM) experiments combined with density functional theory (DFT) calculations reveal that deposited Cr atoms replace either Na or Cl ions, forming substituting dopants in ultrathin NaCl/Au(111) films. The Cr dopants exchange electrons with the support thus changing the electronic properties of the film and in particular the work function. The Cr atoms spontaneously aggregate near the edges of the bilayer (2L) NaCl islands, forming a new phase in the insulator with a remarkably dense population of Cr dopants. The spectra of differential conductance yield evidence that, compared to the undoped or Cr-poor 2L NaCl films on Au(111), the Cr-rich region shows different interface states, shifted image-potential states, and a reduced work function. This demonstrates the potential of doping ultrathin films to modify their adsorption properties in a desired manner.
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Affiliation(s)
- Zhe Li
- Laboratory of Solid-State Physics and Magnetism, KU Leuven, Celestijnenlaan 200d - box 2414, B-3001 Leuven, Belgium.
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30
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Yan S, Choi DJ, Burgess JAJ, Rolf-Pissarczyk S, Loth S. Control of quantum magnets by atomic exchange bias. NATURE NANOTECHNOLOGY 2015; 10:40-45. [PMID: 25502311 DOI: 10.1038/nnano.2014.281] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 10/31/2014] [Indexed: 06/04/2023]
Abstract
Mixing of discretized states in quantum magnets has a radical impact on their properties. Managing this effect is key for spintronics in the quantum limit. Magnetic fields can modify state mixing and, for example, mitigate destabilizing effects in single-molecule magnets. The exchange bias field has been proposed as a mechanism for localized control of individual nanomagnets. Here, we demonstrate that exchange coupling with the magnetic tip of a scanning tunnelling microscope provides continuous tuning of spin state mixing in an individual nanomagnet. By directly measuring spin relaxation time with electronic pump-probe spectroscopy, we find that the exchange interaction acts analogously to a local magnetic field that can be applied to a specific atom. It can be tuned in strength by up to several tesla and cancel external magnetic fields, thereby demonstrating the feasibility of complete control over individual quantum magnets with atomically localized exchange coupling.
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Affiliation(s)
- Shichao Yan
- 1] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2] Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Deung-Jang Choi
- 1] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2] Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Jacob A J Burgess
- 1] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2] Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Steffen Rolf-Pissarczyk
- 1] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2] Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
| | - Sebastian Loth
- 1] Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany [2] Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany
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31
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Fransson J, Ren J, Zhu JX. Electrical and thermal control of magnetic exchange interactions. PHYSICAL REVIEW LETTERS 2014; 113:257201. [PMID: 25554904 DOI: 10.1103/physrevlett.113.257201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Indexed: 06/04/2023]
Abstract
We investigate the far-from-equilibrium nature of magnetic anisotropy and exchange interactions between molecular magnets embedded in a tunnel junction. By mapping to an effective spin model, these magnetic interactions can be divided into three types: isotropic Heisenberg, anisotropic Ising, and anisotropic Dzyaloshinski-Moriya contributions, which are attributed to the background nonequilibrium electronic structures. We further demonstrate that both the magnetic self- and exchange interactions can be controlled either electrically by gating and tuning the voltage bias, or thermally by adjusting the temperature bias. We show that the Heisenberg and Ising interactions scale linearly, while the Dzyaloshinski-Moriya interaction scales quadratically, with the molecule-lead coupling strength. The interactions scale linearly with the effective spin polarizations of the leads and the molecular coherence. Our results pave a way for smart control of magnetic exchange interactions at atomic and molecular levels.
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Affiliation(s)
- Jonas Fransson
- Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
| | - Jie Ren
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - Jian-Xin Zhu
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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32
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Spinelli A, Bryant B, Delgado F, Fernández-Rossier J, Otte AF. Imaging of spin waves in atomically designed nanomagnets. NATURE MATERIALS 2014; 13:782-785. [PMID: 24997736 DOI: 10.1038/nmat4018] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 05/28/2014] [Indexed: 06/03/2023]
Abstract
The spin dynamics of all ferromagnetic materials are governed by two types of collective phenomenon: spin waves and domain walls. The fundamental processes underlying these collective modes, such as exchange interactions and magnetic anisotropy, all originate at the atomic scale. However, conventional probing techniques based on neutron and photon scattering provide high resolution in reciprocal space, and thereby poor spatial resolution. Here we present direct imaging of standing spin waves in individual chains of ferromagnetically coupled S = 2 Fe atoms, assembled one by one on a Cu(2)N surface using a scanning tunnelling microscope. We are able to map the spin dynamics of these designer nanomagnets with atomic resolution in two complementary ways. First, atom-to-atom variations of the amplitude of the quantized spin-wave excitations are probed using inelastic electron tunnelling spectroscopy. Second, we observe slow stochastic switching between two opposite magnetization states, whose rate varies strongly depending on the location of the tip along the chain. Our observations, combined with model calculations, reveal that switches of the chain are initiated by a spin-wave excited state that has its antinodes at the edges of the chain, followed by a domain wall shifting through the chain from one end to the other. This approach opens the way towards atomic-scale imaging of other types of spin excitation, such as spinon pairs and fractional end-states, in engineered spin chains.
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Affiliation(s)
- A Spinelli
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - B Bryant
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
| | - F Delgado
- International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, 4715-310 Braga, Portugal
| | - J Fernández-Rossier
- International Iberian Nanotechnology Laboratory (INL), Avenida Mestre José Veiga, 4715-310 Braga, Portugal
| | - A F Otte
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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33
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Bryant B, Spinelli A, Wagenaar JJT, Gerrits M, Otte AF. Local control of single atom magnetocrystalline anisotropy. PHYSICAL REVIEW LETTERS 2013; 111:127203. [PMID: 24093296 DOI: 10.1103/physrevlett.111.127203] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Indexed: 06/02/2023]
Abstract
Individual Fe atoms on a Cu(2)N/Cu(100) surface exhibit strong magnetic anisotropy due to the crystal field. We show that we can controllably enhance or reduce this anisotropy by adjusting the relative position of a second nearby Fe atom, with atomic precision, in a low-temperature scanning tunneling microscope. Local inelastic electron tunneling spectroscopy, combined with a qualitative first-principles model, reveal that the change in uniaxial anisotropy is driven by local strain due to the presence of the second Fe atom.
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Affiliation(s)
- B Bryant
- Department of Quantum Nanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
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34
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Goldberg EC, Flores F. Inelastic tunneling spectroscopy for magnetic atoms and the Kondo resonance. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:225001. [PMID: 23587848 DOI: 10.1088/0953-8984/25/22/225001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The interaction between a single magnetic atom and the metal environment (including a magnetic field) is analyzed by introducing an ionic Hamiltonian combined with an effective crystal-field term, and by using a Green-function equation of motion method. This approach describes the inelastic electron tunneling spectroscopy and the Kondo resonances as due to atomic spin fluctuations associated with electron co-tunneling processes between the leads and the atom. We analyze in the case of Fe on CuN the possible spin fluctuations between states with S = 2 and 3/2 or 5/2 and conclude that the experimentally found asymmetries in the conductance with respect to the applied bias, and its marked structures, are well explained by the 2↔3/2 spin fluctuations. The case of Co is also considered and shown to present, in contrast with Fe, a resonance at the Fermi energy corresponding to a Kondo temperature of 6 K.
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Affiliation(s)
- E C Goldberg
- Instituto de Desarrollo Tecnológico para la Industria Química and Departamento de Materiales, Facultad de Ingeniería Química, CONICET-UNL, Santa Fe, Argentina.
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35
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Fu YS, Xue QK, Wiesendanger R. Spin-resolved splitting of Kondo resonances in the presence of RKKY-type coupling. PHYSICAL REVIEW LETTERS 2012; 108:087203. [PMID: 22463564 DOI: 10.1103/physrevlett.108.087203] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2011] [Indexed: 05/31/2023]
Abstract
We have performed spin-resolved measurements on a Kondo impurity in the presence of RKKY-type exchange coupling. By placing manganese phthalocyanine (MnPc) molecules on Fe-supported Pb islands, a Kondo system is devised which is exchange coupled to a magnetic substrate via conduction electrons in Pb, inducing spin splitting of the Kondo resonance. The spin-polarized nature of the split Kondo resonance and a spin filter effect induced by spin-flip inelastic electron tunneling are revealed by spin-polarized scanning tunneling microscopy and spectroscopy.
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Affiliation(s)
- Ying-Shuang Fu
- Institute of Applied Physics, Hamburg University, Hamburg, Germany.
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36
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Loth S, Baumann S, Lutz CP, Eigler DM, Heinrich AJ. Bistability in atomic-scale antiferromagnets. Science 2012; 335:196-9. [PMID: 22246771 DOI: 10.1126/science.1214131] [Citation(s) in RCA: 242] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Control of magnetism on the atomic scale is becoming essential as data storage devices are miniaturized. We show that antiferromagnetic nanostructures, composed of just a few Fe atoms on a surface, exhibit two magnetic states, the Néel states, that are stable for hours at low temperature. For the smallest structures, we observed transitions between Néel states due to quantum tunneling of magnetization. We sensed the magnetic states of the designed structures using spin-polarized tunneling and switched between them electrically with nanosecond speed. Tailoring the properties of neighboring antiferromagnetic nanostructures enables a low-temperature demonstration of dense nonvolatile storage of information.
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Affiliation(s)
- Sebastian Loth
- IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120, USA.
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37
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May F, Wegewijs MR, Hofstetter W. Interaction of spin and vibrations in transport through single-molecule magnets. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2011; 2:693-8. [PMID: 22043459 PMCID: PMC3201623 DOI: 10.3762/bjnano.2.75] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2011] [Accepted: 09/03/2011] [Indexed: 05/31/2023]
Abstract
We study electron transport through a single-molecule magnet (SMM) and the interplay of its anisotropic spin with quantized vibrational distortions of the molecule. Based on numerical renormalization group calculations we show that, despite the longitudinal anisotropy barrier and small transverse anisotropy, vibrational fluctuations can induce quantum spin-tunneling (QST) and a QST-Kondo effect. The interplay of spin scattering, QST and molecular vibrations can strongly enhance the Kondo effect and induce an anomalous magnetic field dependence of vibrational Kondo side-bands.
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Affiliation(s)
- Falk May
- Institut für Theoretische Physik, Johann Wolfgang Goethe-Universität, 60438 Frankfurt/Main, Germany
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany
| | - Maarten R Wegewijs
- Institut für Theorie der Statistischen Physik, RWTH Aachen, 52056 Aachen, Germany
- Peter Grünberg Institut and JARA - Fundamentals of Information Technology, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Walter Hofstetter
- Institut für Theoretische Physik, Johann Wolfgang Goethe-Universität, 60438 Frankfurt/Main, Germany
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38
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Néel N, Berndt R, Kröger J, Wehling TO, Lichtenstein AI, Katsnelson MI. Two-site Kondo effect in atomic chains. PHYSICAL REVIEW LETTERS 2011; 107:106804. [PMID: 21981521 DOI: 10.1103/physrevlett.107.106804] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Indexed: 05/31/2023]
Abstract
Linear CoCu(n)Co clusters on Cu(111) fabricated by atomic manipulation represent a two-site Kondo system with tunable interaction. Scanning tunneling spectroscopy reveals oscillations of the Kondo temperature T(K) with the number n of Cu atoms for n≥3. Density functional calculations show that the Ruderman-Kittel-Kasuya-Yosida interaction mediated by the Cu chains causes the oscillations. Calculations find ferromagnetic and antiferromagnetic interaction for n=1 and 2, respectively. Both interactions lead to a decrease of T(K) as experimentally observed.
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Affiliation(s)
- N Néel
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, D-24098 Kiel, Germany
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39
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Baumgärtel MME, Hell M, Das S, Wegewijs MR. Transport and accumulation of spin anisotropy. PHYSICAL REVIEW LETTERS 2011; 107:087202. [PMID: 21929200 DOI: 10.1103/physrevlett.107.087202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Indexed: 05/31/2023]
Abstract
We show that spin anisotropy can be transferred to an isotropic system by transport of a spin-quadrupole moment. We derive the quadrupole moment current and continuity equation and study a spin-valve structure consisting of two ferromagnets coupled to a quantum dot probing an impurity spin. The quadrupole backaction on their coupled spin results in spin torques and anisotropic spin relaxation which do not follow from standard spin-current considerations. We demonstrate the detection of the impurity spin by charge transport and its manipulation by electric fields.
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Affiliation(s)
- Michael M E Baumgärtel
- Peter Grünberg Institut, Forschungszentrum Jülich & JARA Jülich Aachen Research Alliance, D-52425 Jülich, Germany
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40
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Dempsey KJ, Ciudad D, Marrows CH. Single electron spintronics. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:3150-3174. [PMID: 21727119 DOI: 10.1098/rsta.2011.0105] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Single electron electronics is now well developed, and allows the manipulation of electrons one-by-one as they tunnel on and off a nanoscale conducting island. In the past decade or so, there have been concerted efforts in several laboratories to construct single electron devices incorporating ferromagnetic components in order to introduce spin functionality. The use of ferromagnetic electrodes with a non-magnetic island can lead to spin accumulation on the island. On the other hand, making the dot also ferromagnetic introduces new physics such as tunnelling magnetoresistance enhancement in the cotunnelling regime and manifestations of the Kondo effect. Such nanoscale islands are also found to have long spin lifetimes. Conventional spintronics makes use of the average spin-polarization of a large ensemble of electrons: this new approach offers the prospect of accessing the quantum properties of the electron, and is a candidate approach to the construction of solid-state spin-based qubits.
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Affiliation(s)
- Kari J Dempsey
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
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41
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Delgado F, Fernández-Rossier J. Inelastic electron tunneling spectroscopy of a single nuclear spin. PHYSICAL REVIEW LETTERS 2011; 107:076804. [PMID: 21902416 DOI: 10.1103/physrevlett.107.076804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Indexed: 05/31/2023]
Abstract
Detection of a single nuclear spin constitutes an outstanding problem in different fields of physics such as quantum computing or magnetic imaging. Here we show that the energy levels of a single nuclear spin can be measured by means of inelastic electron tunneling spectroscopy (IETS). We consider two different systems, a magnetic adatom probed with scanning tunneling microscopy and a single Bi dopant in a silicon nanotransistor. We find that the hyperfine coupling opens new transport channels which can be resolved at experimentally accessible temperatures. Our simulations evince that IETS yields information about the occupations of the nuclear spin states, paving the way towards transport-detected single nuclear spin resonance.
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Affiliation(s)
- F Delgado
- Departamento de Física Aplicada, Universidad de Alicante, San Vicente del Raspeig, Spain
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42
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Eichler A, Weiss M, Schönenberger C. Gate-tunable split Kondo effect in a carbon nanotube quantum dot. NANOTECHNOLOGY 2011; 22:265204. [PMID: 21576773 DOI: 10.1088/0957-4484/22/26/265204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We show a detailed investigation of the split Kondo effect in a carbon nanotube quantum dot with multiple gate electrodes. Two conductance peaks, observed at finite bias in nonlinear transport measurements, are found to approach each other for increasing magnetic field, to result in a recovered zero bias Kondo resonance at finite magnetic field. Surprisingly, in the same charge state, but under different gate configurations, the splitting does not disappear for any value of the magnetic field, but we observe an avoided crossing. We think that our observations can be understood in terms of a two-impurity Kondo effect with two spins coupled antiferromagnetically. The exchange coupling between the two spins can be influenced by a local gate, and the non-recovery of the Kondo resonance for certain gate configurations is explained by the existence of a small antisymmetric contribution to the exchange interaction between the two spins.
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Affiliation(s)
- A Eichler
- Department of Physics, University of Basel, Basel, Switzerland
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43
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Tsukahara N, Shiraki S, Itou S, Ohta N, Takagi N, Kawai M. Evolution of Kondo resonance from a single impurity molecule to the two-dimensional lattice. PHYSICAL REVIEW LETTERS 2011; 106:187201. [PMID: 21635122 DOI: 10.1103/physrevlett.106.187201] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 03/09/2011] [Indexed: 05/30/2023]
Abstract
The successive spectral evolution of the Kondo resonance state was investigated from a single iron(II) phthalocyanine molecule to the two-dimensional lattice on Au(111) by interrogating the individual molecules with a scanning tunneling microscope. A sharp Kondo peak appears in the single-impurity regime, which broadens and splits as the lattice builds up. The origin of spectral evolution together with the electronic ground state of the lattice are discussed based on the competition of the Kondo effect and Rudermann-Kittel-Kasuya-Yosida coupling between the molecular spins.
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Affiliation(s)
- Noriyuki Tsukahara
- Department of Advanced Materials Science, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba, Japan
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44
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Andergassen S, Meden V, Schoeller H, Splettstoesser J, Wegewijs MR. Charge transport through single molecules, quantum dots and quantum wires. NANOTECHNOLOGY 2010; 21:272001. [PMID: 20571187 DOI: 10.1088/0957-4484/21/27/272001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We review recent progress in the theoretical description of correlation and quantum fluctuation phenomena in charge transport through single molecules, quantum dots and quantum wires. Various physical phenomena are addressed, relating to cotunneling, pair-tunneling, adiabatic quantum pumping, charge and spin fluctuations, and inhomogeneous Luttinger liquids. We review theoretical many-body methods to treat correlation effects, quantum fluctuations, non-equilibrium physics, and the time evolution into the stationary state of complex nanoelectronic systems.
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Affiliation(s)
- S Andergassen
- Institut für Theoretische Physik A, RWTH Aachen, 52056 Aachen, Germany
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