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Pelliciari J, Mejia E, Woods JM, Gu Y, Li J, Chand SB, Fan S, Watanabe K, Taniguchi T, Bisogni V, Grosso G. Elementary excitations of single-photon emitters in hexagonal boron nitride. NATURE MATERIALS 2024; 23:1230-1236. [PMID: 38654140 DOI: 10.1038/s41563-024-01866-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 03/15/2024] [Indexed: 04/25/2024]
Abstract
Single-photon emitters serve as building blocks for many emerging concepts in quantum photonics. The recent identification of bright, tunable and stable emitters in hexagonal boron nitride (hBN) has opened the door to quantum platforms operating across the infrared to ultraviolet spectrum. Although it is widely acknowledged that defects are responsible for single-photon emitters in hBN, crucial details regarding their origin, electronic levels and orbital involvement remain unknown. Here we employ a combination of resonant inelastic X-ray scattering and photoluminescence spectroscopy in defective hBN, unveiling an elementary excitation at 285 meV that gives rise to a plethora of harmonics correlated with single-photon emitters. We discuss the importance of N π* anti-bonding orbitals in shaping the electronic states of the emitters. The discovery of elementary excitations in hBN provides fundamental insights into quantum emission in low-dimensional materials, paving the way for future investigations in other platforms.
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Affiliation(s)
- Jonathan Pelliciari
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA.
| | - Enrique Mejia
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York City, NY, USA
| | - John M Woods
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York City, NY, USA
| | - Yanhong Gu
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA
| | - Jiemin Li
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA
| | - Saroj B Chand
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York City, NY, USA
| | - Shiyu Fan
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, Tsukuba, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - Valentina Bisogni
- National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY, USA
| | - Gabriele Grosso
- Photonics Initiative, Advanced Science Research Center, City University of New York, New York City, NY, USA.
- Physics Program, Graduate Center, City University of New York, New York, NY, USA.
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2
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Feygenson M, Huang Z, Xiao Y, Teng X, Lohstroh W, Nandakumaran N, Neuefeind JC, Everett M, Podlesnyak AA, Salazar-Alvarez G, Ulusoy S, Valvo M, Su Y, Ehlert S, Qdemat A, Ganeva M, Zhang L, Aronson MC. Probing spin waves in Co 3O 4 nanoparticles for magnonics applications. NANOSCALE 2024; 16:1291-1303. [PMID: 38131194 DOI: 10.1039/d3nr04424f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
The magnetic properties of spinel nanoparticles can be controlled by synthesizing particles of a specific shape and size. The synthesized nanorods, nanodots and cubic nanoparticles have different crystal planes selectively exposed on the surface. The surface effects on the static magnetic properties are well documented, while their influence on spin waves dispersion is still being debated. Our ability to manipulate spin waves using surface and defect engineering in magnetic nanoparticles is the key to designing magnonic devices. We synthesized cubic and spherical nanoparticles of a classical antiferromagnetic material Co3O4 to study the shape and size effects on their static and dynamic magnetic proprieties. Using a combination of experimental methods, we probed the magnetic and crystal structures of our samples and directly measured spin wave dispersions using inelastic neutron scattering. We found a weak, but unquestionable, increase in exchange interactions for the cubic nanoparticles as compared to spherical nanoparticle and bulk powder reference samples. Interestingly, the exchange interactions in spherical nanoparticles have bulk-like properties, despite a ferromagnetic contribution from canted surface spins.
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Affiliation(s)
- Mikhail Feygenson
- European Spallation Source ERIC, SE-221 00 Lund, Sweden.
- Jülich Centre for Neutron Science (JCNS-1) at Forschungszentrum Jülich, D-52425 Jülich, Germany
- Department of Materials Science and Engineering, Uppsala University, Box 35, 751 03, Uppsala, Sweden
| | - Zhongyuan Huang
- School of Advanced Materials, Peking University, Shenzhen Graduate School, Shenzhen 518055, China
| | - Yinguo Xiao
- School of Advanced Materials, Peking University, Shenzhen Graduate School, Shenzhen 518055, China
| | - Xiaowei Teng
- Worcester Polytechnic Institute, Department of Chemical Engineering, Worcester 01609, USA
| | - Wiebke Lohstroh
- Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, 8574 Garching, Germany
| | - Nileena Nandakumaran
- Jülich Centre for Neutron Science (JCNS-2) and Peter Grünberg Institute (PGI-4), Jülich GmbH, 52425, Jülich, Germany
| | - Jörg C Neuefeind
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Michelle Everett
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Andrey A Podlesnyak
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Germán Salazar-Alvarez
- Department of Materials Science and Engineering, Uppsala University, Box 35, 751 03, Uppsala, Sweden
| | - Seda Ulusoy
- Department of Materials Science and Engineering, Uppsala University, Box 35, 751 03, Uppsala, Sweden
| | - Mario Valvo
- Department of Chemistry, Uppsala University, 75121 Uppsala, Sweden
| | - Yixi Su
- Jülich Centre for Neutron Science (JCNS-4) at Heinz Maier-Leibnitz-Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85747 Garching, Germany
| | - Sascha Ehlert
- Jülich Centre for Neutron Science (JCNS-1) at Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Asma Qdemat
- Jülich Centre for Neutron Science (JCNS-2) and Peter Grünberg Institute (PGI-4), Jülich GmbH, 52425, Jülich, Germany
| | - Marina Ganeva
- Jülich Centre for Neutron Science (JCNS-4) at Heinz Maier-Leibnitz-Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85747 Garching, Germany
| | - Lihua Zhang
- Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973-5000, USA
| | - Meigan C Aronson
- Stewart Blusson Quantum Matter Institute, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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3
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Bondarev IV, Pugh MD, Rodriguez-Lopez P, Woods LM, Antezza M. Confinement-induced nonlocality and casimir force in transdimensional systems. Phys Chem Chem Phys 2023; 25:29257-29265. [PMID: 37874297 DOI: 10.1039/d3cp03706a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
We study within the framework of the Lifshitz theory the long-range Casimir force for in-plane isotropic and anisotropic free-standing transdimensional material slabs. In the former case, we show that the confinement-induced nonlocality not only weakens the attraction of ultrathin slabs but also changes the distance dependence of the material-dependent correction to the Casimir force to go as contrary to the ∼1/l dependence of that of the local Lifshitz force. In the latter case, we use closely packed array of parallel aligned single-wall carbon nanotubes in a dielectric layer of finite thickness to demonstrate strong orientational anisotropy and crossover behavior for the inter-slab attractive force in addition to its reduction with decreasing slab thickness. We give physical insight as to why such a pair of ultrathin slabs prefers to stick together in the perpendicularly oriented manner, rather than in the parallel relative orientation as one would customarily expect.
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Affiliation(s)
- Igor V Bondarev
- Department of Mathematics & Physics, North Carolina Central University, Durham, NC 27707, USA.
| | - Michael D Pugh
- Department of Mathematics & Physics, North Carolina Central University, Durham, NC 27707, USA.
| | - Pablo Rodriguez-Lopez
- Área de Electromagnetismo and Grupo Interdisciplinar de Sistemas Complejos (GISC), Universidad Rey Juan Carlos, 28933 Móstoles, Madrid, Spain
- Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS-University of Montpellier, F-34095 Montpellier, France
| | - Lilia M Woods
- Department of Physics, University of South Florida, Tampa, FL 33620, USA
| | - Mauro Antezza
- Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS-University of Montpellier, F-34095 Montpellier, France
- Institut Universitaire de France, 1 rue Descartes, F-75231 Paris Cedex 05, France
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4
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Tseng Y, Paris E, Schmidt KP, Zhang W, Asmara TC, Bag R, Strocov VN, Singh S, Schlappa J, Rønnow HM, Schmitt T. Momentum-resolved spin-conserving two-triplon bound state and continuum in a cuprate ladder. COMMUNICATIONS PHYSICS 2023; 6:138. [PMID: 38665396 PMCID: PMC11041747 DOI: 10.1038/s42005-023-01250-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 05/23/2023] [Indexed: 04/28/2024]
Abstract
Studying multi-particle elementary excitations has provided unique access to understand collective many-body phenomena in correlated electronic materials, paving the way towards constructing microscopic models. In this work, we perform O K-edge resonant inelastic X-ray scattering (RIXS) on the quasi-one-dimensional cuprate Sr 14 Cu 24 O 41 with weakly-doped spin ladders. The RIXS signal is dominated by a dispersing sharp mode ~ 270 meV on top of a damped incoherent component ~ 400-500 meV. Comparing with model calculations using the perturbative continuous unitary transformations method, the two components resemble the spin-conserving ΔS = 0 two-triplon bound state and continuum excitations in the spin ladders. Such multi-spin response with long-lived ΔS = 0 excitons is central to several exotic magnetic properties featuring Majorana fermions, yet remains unexplored given the generally weak cross-section with other experimental techniques. By investigating a simple spin-ladder model system, our study provides valuable insight into low-dimensional quantum magnetism.
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Affiliation(s)
- Yi Tseng
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
- Laboratory for Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Present Address: Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Eugenio Paris
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Kai P. Schmidt
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Staudtstraße 7, D-91058 Erlangen, Germany
| | - Wenliang Zhang
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Teguh Citra Asmara
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Rabindranath Bag
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra 411008 India
- Present Address: Department of Physics, Duke University, Durham, NC 27708 USA
| | - Vladimir N. Strocov
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
| | - Surjeet Singh
- Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune, Maharashtra 411008 India
| | - Justine Schlappa
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
- European X-Ray Free-Electron Laser Facility GmbH, Holzkoppel 4, 22869 Schenefeld, Germany
| | - Henrik M. Rønnow
- Laboratory for Quantum Magnetism, Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Thorsten Schmitt
- Photon Science Division, Paul Scherrer Institut, Forschungstrasse 111, CH-5232 Villigen PSI, Switzerland
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5
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Chen L, Mankovsky S, Kronseder M, Schuh D, Prager M, Bougeard D, Ebert H, Weiss D, Back CH. Interfacial Tuning of Anisotropic Gilbert Damping. PHYSICAL REVIEW LETTERS 2023; 130:046704. [PMID: 36763433 DOI: 10.1103/physrevlett.130.046704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 10/17/2022] [Accepted: 01/09/2023] [Indexed: 06/18/2023]
Abstract
Tuning of the anisotropic Gilbert damping Δα has been realized in ultrathin single-crystalline Fe films grown on GaAs (001). A nonmonotonic dependence of Δα on film thickness t is observed upon varying t about 10 ML (∼1.4 nm). Δα increases for 16 ML>t>8.5 ML, and then decreases for 8.5 ML>t>6.5 ML accompanied by a sign reversal of Δα for t=6.5 ML. The sign reversal of Δα is captured by first-principle calculations, which show that the anisotropic density of states changes sign upon decreasing t. Moreover, t^{-1} dependence of the anisotropic damping indicates the emergence of an anisotropic effective spin mixing conductance according to the theory of spin pumping. The results establish new opportunities for controlling the Gilbert damping and for fundamental studies of magnetization dynamics in reduced dimension.
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Affiliation(s)
- L Chen
- Department of Physics, Technical University of Munich, Munich, Germany
| | - S Mankovsky
- Department of Chemistry, Ludwig Maximilian University, Munich, Germany
| | - M Kronseder
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany
| | - D Schuh
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany
| | - M Prager
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany
| | - D Bougeard
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany
| | - H Ebert
- Department of Chemistry, Ludwig Maximilian University, Munich, Germany
| | - D Weiss
- Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany
| | - C H Back
- Department of Physics, Technical University of Munich, Munich, Germany
- Center for Quantum Engineering (ZQE), Technical University of Munich, Munich, Germany
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6
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Gilmore K. Quantifying vibronic coupling with resonant inelastic X-ray scattering. Phys Chem Chem Phys 2023; 25:217-231. [DOI: 10.1039/d2cp00968d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Electron–phonon interactions are fundamental to the behavior of chemical and physical systems.
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Affiliation(s)
- Keith Gilmore
- Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Zum Großen Windkanal 2, 12489 Berlin, Germany
- European Theoretical Spectroscopy Facility (ETSF), Berlin, Germany
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7
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Nag A, Peng Y, Li J, Agrestini S, Robarts HC, García-Fernández M, Walters AC, Wang Q, Yin Q, Lei H, Yin Z, Zhou KJ. Correlation driven near-flat band Stoner excitations in a Kagome magnet. Nat Commun 2022; 13:7317. [DOI: 10.1038/s41467-022-34933-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Accepted: 11/11/2022] [Indexed: 11/29/2022] Open
Abstract
AbstractAmong condensed matter systems, Mott insulators exhibit diverse properties that emerge from electronic correlations. In itinerant metals, correlations are usually weak, but can also be enhanced via geometrical confinement of electrons, that manifest as ‘flat’ dispersionless electronic bands. In the fast developing field of topological materials, which includes Dirac and Weyl semimetals, flat bands are one of the important components that can result in unusual magnetic and transport behaviour. To date, characterisation of flat bands and their magnetism is scarce, hindering the design of novel materials. Here, we investigate the ferromagnetic Kagomé semimetal Co3Sn2S2 using resonant inelastic X-ray scattering. Remarkably, nearly non-dispersive Stoner spin excitation peaks are observed, sharply contrasting with the featureless Stoner continuum expected in conventional ferromagnetic metals. Our band structure and dynamic spin susceptibility calculations, and thermal evolution of the excitations, confirm the nearly non-dispersive Stoner excitations as unique signatures of correlations and spin-polarized electronic flat bands in Co3Sn2S2. These observations serve as a cornerstone for further exploration of band-induced symmetry-breaking orders in topological materials.
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8
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Stamps R. Probing a mesoscopic elephant. NATURE MATERIALS 2021; 20:127-128. [PMID: 33462467 DOI: 10.1038/s41563-020-00915-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Affiliation(s)
- Robert Stamps
- Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada.
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