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Tai JSB, Hess AJ, Wu JS, Smalyukh II. Field-controlled dynamics of skyrmions and monopoles. SCIENCE ADVANCES 2024; 10:eadj9373. [PMID: 38277460 PMCID: PMC10816702 DOI: 10.1126/sciadv.adj9373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 12/26/2023] [Indexed: 01/28/2024]
Abstract
Magnetic monopoles, despite their ongoing experimental search as elementary particles, have inspired the discovery of analogous excitations in condensed matter systems. In chiral condensed matter systems, emergent monopoles are responsible for the onset of transitions between topologically distinct states and phases, such as in the case of transitions from helical and conical phase to A-phase comprising periodic arrays of skyrmions. By combining numerical modeling and optical characterizations, we describe how different geometrical configurations of skyrmions terminating at monopoles can be realized in liquid crystals and liquid crystal ferromagnets. We demonstrate how these complex structures can be effectively manipulated by external magnetic and electric fields. Furthermore, we discuss how our findings may hint at similar dynamics in other physical systems and their potential applications.
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Affiliation(s)
- Jung-Shen B. Tai
- Department of Physics and Chemical Physics Program, University of Colorado, Boulder, CO 80309, USA
| | - Andrew J. Hess
- Department of Physics and Chemical Physics Program, University of Colorado, Boulder, CO 80309, USA
| | - Jin-Sheng Wu
- Department of Physics and Chemical Physics Program, University of Colorado, Boulder, CO 80309, USA
| | - Ivan I. Smalyukh
- Department of Physics and Chemical Physics Program, University of Colorado, Boulder, CO 80309, USA
- Department of Electrical, Computer, and Energy Engineering, Materials Science and Engineering Program and Soft Materials Research Center, University of Colorado, Boulder, CO 80309, USA
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, CO 80309, USA
- International Institute for Sustainability with Knotted Chiral Meta Matter (WPI-SKCM), Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8526, Japan
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2
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Tasinkevych M, Park S, Mundoor H, Smalyukh II. Nanoparticle localization within chiral liquid crystal defect lines and nanoparticle interactions. Phys Rev E 2023; 107:034701. [PMID: 37073031 DOI: 10.1103/physreve.107.034701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 02/21/2023] [Indexed: 04/20/2023]
Abstract
Self-assembly of colloidal particles into predefined structures is a promising way to design inexpensive manmade materials with advanced macroscopic properties. Doping of nematic liquid crystals (LCs) with nanoparticles has a series of advantages in addressing these grand scientific and engineering challenges. It also provides a very rich soft matter platform for the discovery of unique condensed matter phases. The LC host naturally allows the realization of diverse anisotropic interparticle interactions, enriched by the spontaneous alignment of anisotropic particles due to the boundary conditions of the LC director. Here we demonstrate theoretically and experimentally that the ability of LC media to host topological defect lines can be used as a tool to probe the behavior of individual nanoparticles as well as effective interactions between them. LC defect lines irreversibly trap nanoparticles enabling controlled particle movement along the defect line with the use of a laser tweezer. Minimization of Landau-de Gennes free energy reveals a sensitivity of the ensuing effective nanoparticle interaction to the shape of the particle, surface anchoring strength, and temperature, which determine not only the strength of the interaction but also its repulsive or attractive character. Theoretical results are supported qualitatively by experimental observations. This work may pave the way toward designing controlled linear assemblies as well as one-dimensional crystals of nanoparticles such as gold nanorods or quantum dots with tunable interparticle spacing.
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Affiliation(s)
- Mykola Tasinkevych
- SOFT Group, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham NG11 8NS, United Kingdom
- Departamento de Física, and Centro de Física Teórica e Computacional, Faculdade de Ciências, Universidade de Lisboa, 1749-016 Lisboa, Portugal
- International Institute for Sustainability with Knotted Chiral Meta Matter, Hiroshima University, Higashihiroshima 739-8511, Japan
| | - Sungoh Park
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Haridas Mundoor
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Ivan I Smalyukh
- International Institute for Sustainability with Knotted Chiral Meta Matter, Hiroshima University, Higashihiroshima 739-8511, Japan
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- Soft Materials Research Center; Department of Electrical, Computer, and Energy Engineering and Materials Science and Engineering Program; and Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory, University of Colorado, Boulder, Colorado 80309, USA
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3
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Rhee K, Tukova A, Tavakkoli Yaraki M, Wang Y. Nanosupernova: a new anisotropic nanostructure for SERS. NANOSCALE 2023; 15:2087-2095. [PMID: 36647920 DOI: 10.1039/d2nr05287c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Gold and/or silver nanostars are interesting anisotropic nanoparticles that have been used in surface-enhanced Raman scattering (SERS). In particular SERS nanotags consisting of gold nanostars and Raman reporter molecules have been widely utilised in biosensing and bioimaging. To improve the SERS activity of gold/silver nanostars, this paper details the development of a simple synthesis method that results in the formation of quasi-spherical SERS nanotags and larger highly anisotropic nanoparticles with a novel structure, which we have designated nanosupernova. The resulting SERS nanotags and nanosupernova contain gold/silver nanostars at their core, a self-assembled monolayer of Raman reporter molecules, and a final silver coating. The silver coating is the essential step responsible for the formation of the two types of particles, with incubation time, and type of Raman reporter molecule, the defining factor as to which forms. We discovered that the Raman reporter molecule, 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB), plays a crucial role in controlling the morphology of nanosupernova. We believe the larger highly anisotropic nanoparticles will open new applications in material sciences and in optical and electronic devices in the future.
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Affiliation(s)
- Kristina Rhee
- School of Natural Sciences, Faculty of Science and Engineering, Macquarie University, Ryde, New South Wales 2109, Australia.
| | - Anastasiia Tukova
- School of Natural Sciences, Faculty of Science and Engineering, Macquarie University, Ryde, New South Wales 2109, Australia.
| | - Mohammad Tavakkoli Yaraki
- School of Natural Sciences, Faculty of Science and Engineering, Macquarie University, Ryde, New South Wales 2109, Australia.
| | - Yuling Wang
- School of Natural Sciences, Faculty of Science and Engineering, Macquarie University, Ryde, New South Wales 2109, Australia.
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Liu Q, Mundoor H, Sheetah GH, Smalyukh II. Plasmonic gold-cellulose nanofiber aerogels. OPTICS EXPRESS 2020; 28:34237-34245. [PMID: 33182897 DOI: 10.1364/oe.399181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Assembly of plasmonic nanomaterials into a low refractive index medium, such as an aerogel, holds a great promise for optical metamaterials, optical sensors, and photothermal energy converters. However, conventional plasmonic aerogels are opaque and optically isotropic composites, impeding them from being used as low-loss or polarization-dependent optical materials. Here we demonstrate a plasmonic-cellulose nanofiber composite aerogel that comprises of well-dispersed gold nanorods within a cellulose nanofiber network. The cellulose aerogel host is highly transparent owing to the small scattering cross-section of the nanofibers and forms a nematic liquid crystalline medium with strong optical birefringence. We find that the longitudinal surface plasmon resonance peak of gold nanorods shows a dramatic shift when probed for the cellulose aerogel compared with the wet gels. Simulations reveal the shift of surface plasmon resonance peak with gel drying can be attributed to the change of the effective refractive index of the gels. This composite material may provide a platform for three- dimensional plasmonic devices ranging from optical sensors to metamaterials.
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Mundoor H, Cruz-Colón EM, Park S, Liu Q, Smalyukh II, van de Lagemaat J. Control of quantum dot emission by colloidal plasmonic pyramids in a liquid crystal. OPTICS EXPRESS 2020; 28:5459-5469. [PMID: 32121766 DOI: 10.1364/oe.383672] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 01/25/2020] [Indexed: 06/10/2023]
Abstract
We study the plasmon-enhanced fluorescence of a single semiconducting quantum dot near the apex of a colloidal gold pyramid spatially localized by the elastic forces of the liquid crystal host. The gold pyramid particles were manipulated within the liquid crystal medium by laser tweezers, enabling the self-assembly of a semiconducting quantum dot dispersed in the medium near the apex of the gold pyramid, allowing us to probe the plasmon-exciton interactions. We demonstrate the effect of plasmon coupling on the fluorescence lifetime and the blinking properties of the quantum dot. Our results demonstrate that topological defects around colloidal particles in liquid crystal combined with laser tweezers provide a platform for plasmon exciton interaction studies and potentially could be extended to the scale of composite materials for nanophotonic applications.
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Hess A, Funk AJ, Liu Q, De La Cruz JA, Sheetah GH, Fleury B, Smalyukh II. Plasmonic Metamaterial Gels with Spatially Patterned Orientational Order via 3D Printing. ACS OMEGA 2019; 4:20558-20563. [PMID: 31858040 PMCID: PMC6906772 DOI: 10.1021/acsomega.9b02418] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 11/04/2019] [Indexed: 05/08/2023]
Abstract
Optical properties can be programmed on mesoscopic scales by patterning host materials while ordering their nanoparticle inclusions. While liquid crystals are often used to define the ordering of nanoparticles dispersed within them, this approach is typically limited to liquid crystals confined in classic geometries. In this work, the orientational order that liquid crystalline colloidal hosts impose on anisotropic nanoparticle inclusions is combined with an additive manufacturing method that enables engineered, macroscopic three-dimensional (3D) patterns of co-aligned gold nanorods and cellulose nanocrystals. These gels exhibit polarization-dependent plasmonic properties that emerge from the unique interaction between the host medium's anisotropic optical properties defined by orientationally ordered cellulose nanocrystals, from the liquid crystal's gold nanorod inclusions, and from the complexity of spatial patterns accessed with 3D printing. The gels' optical properties that are defined by the interplay of these effects are tuned by controlling the gels' order, which is tuned by adjusting the gels' cellulose nanocrystal concentrations. Lithe optical responsiveness of these composite gels to polarized radiation may enable unique technological applications like polarization-sensitive optical elements.
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Affiliation(s)
- Andrew
J. Hess
- Department
of Physics, 390 UCB, University of Colorado
Boulder, Boulder, Colorado 80309, United States
| | - Andrew J. Funk
- Department
of Physics, 390 UCB, University of Colorado
Boulder, Boulder, Colorado 80309, United States
| | - Qingkun Liu
- Department
of Physics, 390 UCB, University of Colorado
Boulder, Boulder, Colorado 80309, United States
| | - Joshua A. De La Cruz
- Materials
Science and Engineering, 027 UCB, Sustainability, Energy & Environment
Community, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Ghadah H. Sheetah
- Materials
Science and Engineering, 027 UCB, Sustainability, Energy & Environment
Community, University of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Blaise Fleury
- Department
of Physics, 390 UCB, University of Colorado
Boulder, Boulder, Colorado 80309, United States
| | - Ivan I. Smalyukh
- Department
of Physics, 390 UCB, University of Colorado
Boulder, Boulder, Colorado 80309, United States
- Materials
Science and Engineering, 027 UCB, Sustainability, Energy & Environment
Community, University of Colorado Boulder, Boulder, Colorado 80303, United States
- Renewable
and Sustainable Energy Institute, National
Renewable Energy Laboratory and University of Colorado, Boulder, Colorado 80309, United States
- E-mail:
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7
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Senyuk B, Aplinc J, Ravnik M, Smalyukh II. High-order elastic multipoles as colloidal atoms. Nat Commun 2019; 10:1825. [PMID: 31015420 PMCID: PMC6478862 DOI: 10.1038/s41467-019-09777-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/28/2019] [Indexed: 11/09/2022] Open
Abstract
Achieving and exceeding diversity of colloidal analogs of chemical elements and molecules as building blocks of matter has been the central goal and challenge of colloidal science ever since Einstein introduced the colloidal atom paradigm. Recent advances in colloids assembly have been achieved by exploiting the machinery of DNA hybridization but robust physical means of defining colloidal elements remain limited. Here we introduce physical design principles allowing us to define high-order elastic multipoles emerging when colloids with controlled shapes and surface alignment are introduced into a nematic host fluid. Combination of experiments and numerical modeling of equilibrium field configurations using a spherical harmonic expansion allow us to probe elastic multipole moments, bringing analogies with electromagnetism and a structure of atomic orbitals. We show that, at least in view of the symmetry of the "director wiggle wave functions," diversity of elastic colloidal atoms can far exceed that of known chemical elements.
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Affiliation(s)
- Bohdan Senyuk
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO, 80309, USA
| | - Jure Aplinc
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000, Ljubljana, Slovenia
| | - Miha Ravnik
- Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000, Ljubljana, Slovenia.,J. Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
| | - Ivan I Smalyukh
- Department of Physics and Soft Materials Research Center, University of Colorado, Boulder, CO, 80309, USA. .,Department of Electrical, Computer and Energy Engineering, University of Colorado, Boulder, CO, 80309, USA. .,Renewable and Sustainable Energy Institute, University of Colorado, Boulder, CO, 80309, USA.
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8
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Sohn HRO, Ackerman PJ, Boyle TJ, Sheetah GH, Fornberg B, Smalyukh II. Dynamics of topological solitons, knotted streamlines, and transport of cargo in liquid crystals. Phys Rev E 2018; 97:052701. [PMID: 29906829 DOI: 10.1103/physreve.97.052701] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Indexed: 06/08/2023]
Abstract
Active colloids and liquid crystals are capable of locally converting the macroscopically supplied energy into directional motion and promise a host of new applications, ranging from drug delivery to cargo transport at the mesoscale. Here we uncover how topological solitons in liquid crystals can locally transform electric energy to translational motion and allow for the transport of cargo along directions dependent on frequency of the applied electric field. By combining polarized optical video microscopy and numerical modeling that reproduces both the equilibrium structures of solitons and their temporal evolution in applied fields, we uncover the physical underpinnings behind this reconfigurable motion and study how it depends on the structure and topology of solitons. We show that, unexpectedly, the directional motion of solitons with and without the cargo arises mainly from the asymmetry in rotational dynamics of molecular ordering in liquid crystal rather than from the asymmetry of fluid flows, as in conventional active soft matter systems.
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Affiliation(s)
- Hayley R O Sohn
- Soft Materials Research Center and Materials Science and Engineering Program, University of Colorado, Boulder, Colorado 80309, USA
| | - Paul J Ackerman
- Department of Physics and Department of Electrical, Computer and Energy Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - Timothy J Boyle
- Department of Physics and Department of Electrical, Computer and Energy Engineering, University of Colorado, Boulder, Colorado 80309, USA
| | - Ghadah H Sheetah
- Soft Materials Research Center and Materials Science and Engineering Program, University of Colorado, Boulder, Colorado 80309, USA
| | - Bengt Fornberg
- Department of Applied Mathematics, University of Colorado, Boulder, Colorado 80309, USA
| | - Ivan I Smalyukh
- Soft Materials Research Center and Materials Science and Engineering Program, University of Colorado, Boulder, Colorado 80309, USA
- Department of Physics and Department of Electrical, Computer and Energy Engineering, University of Colorado, Boulder, Colorado 80309, USA
- Renewable and Sustainable Energy Institute, National Renewable Energy Laboratory and University of Colorado, Boulder, Colorado 80309, USA
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Mundoor H, Sheetah GH, Park S, Ackerman PJ, Smalyukh II, van de Lagemaat J. Tuning and Switching a Plasmonic Quantum Dot "Sandwich" in a Nematic Line Defect. ACS NANO 2018; 12:2580-2590. [PMID: 29489324 DOI: 10.1021/acsnano.7b08462] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We study the quantum-mechanical effects arising in a single semiconductor core/shell quantum dot (QD) controllably sandwiched between two plasmonic nanorods. Control over the position and the "sandwich" confinement structure is achieved by the use of a linear-trap liquid crystal (LC) line defect and laser tweezers that "push" the sandwich together. This arrangement allows for the study of exciton-plasmon interactions in a single structure, unaltered by ensemble effects or the complexity of dielectric interfaces. We demonstrate the effect of plasmonic confinement on the photon antibunching behavior of the QD and its luminescence lifetime. The QD behaves as a single emitter when nanorods are far away from the QD but shows possible multiexciton emission and a significantly decreased lifetime when tightly confined in a plasmonic "sandwich". These findings demonstrate that LC defects, combined with laser tweezers, enable a versatile platform to study plasmonic coupling phenomena in a nanoscale laboratory, where all elements can be arranged almost at will.
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Affiliation(s)
| | | | | | | | - Ivan I Smalyukh
- Renewable and Sustainable Energy Institute , National Renewable Energy Laboratory and University of Colorado , Boulder , Colorado 80309 , United States
| | - Jao van de Lagemaat
- Renewable and Sustainable Energy Institute , National Renewable Energy Laboratory and University of Colorado , Boulder , Colorado 80309 , United States
- National Renewable Energy Laboratory , Golden , Colorado 80401 , United States
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Abstract
Skyrmions are topologically protected continuous field configurations that cannot be smoothly transformed to a uniform state. They behave like particles and give origins to the field of skyrmionics that promises racetrack memory and other technological applications. Unraveling the non-equilibrium behavior of such topological solitons is a challenge. We realize skyrmions in a chiral liquid crystal and, using numerical modeling and polarized video microscopy, demonstrate electrically driven squirming motion. We reveal the intricate details of non-equilibrium topology-preserving textural changes driving this behavior. Direction of the skyrmion’s motion is robustly controlled in a plane orthogonal to the applied field and can be reversed by varying frequency. Our findings may spur a paradigm of soliton dynamics in soft matter, with a rich interplay between topology, chirality, and orientational viscoelasticity. A skyrmion is a topological object originally introduced to model elementary particles and a baby skyrmion is its two-dimensional counterpart which can be realized as a defect in liquid crystals. Here the authors show that an electric field can drive uniform motion of baby skyrmions in liquid crystals.
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Dey S, Zhao J. Plasmonic Effect on Exciton and Multiexciton Emission of Single Quantum Dots. J Phys Chem Lett 2016; 7:2921-9. [PMID: 27411778 DOI: 10.1021/acs.jpclett.6b01164] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Quantum dots are nanoscale quantum emitters with high quantum yield and size-dependent emission wavelength, holding promises in many optical and electronic applications. When quantum dots are situated close to noble metal nanoparticles, their emitting behavior can be conveniently tuned because of the interaction between the excitons of the quantum dots and the plasmons of the metal nanoparticles. This interaction at the single quantum dot level gives rise to reduced or suppressed photoluminescence blinking and enhanced multiexciton emission, which is difficult to achieve in isolated quantum dots. However, the mechanism of how plasmonic structures cause the changes in the quantum dot emission remains unclear. Because of the complexity of the system, the interfaces between metal, semiconductor, and ligands must be considered, in addition to factors such as geometry, interparticle distance, and spectral overlap. The challenges in the design and fabrication of the hybrid nanostructures as well as in understanding the exciton-plasmon coupling mechanism can be overcome by a cooperative effort in synthesis, optical spectroscopy, and theoretical modeling.
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Affiliation(s)
- Swayandipta Dey
- Department of Chemistry, University of Connecticut , 55 North Eagleville Road, Storrs, Connecticut 06269-3060, United States
| | - Jing Zhao
- Department of Chemistry, University of Connecticut , 55 North Eagleville Road, Storrs, Connecticut 06269-3060, United States
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