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Gogoi P, Kamenskyi D, Arslanov DD, Jongma RT, van der Zande WJ, Redlich B, van der Meer AFG, Engelkamp H, Christianen PCM, Maan JC. Magnetoquantum Oscillations at THz Frequencies in InSb. Phys Rev Lett 2017; 119:146603. [PMID: 29053326 DOI: 10.1103/physrevlett.119.146603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Indexed: 06/07/2023]
Abstract
The ac magnetoconductance of bulk InSb at THz frequencies in high magnetic fields, as measured by the transmission of THz radiation, shows a field-induced transmission, which at high temperatures (≈100 K) is well explained with classical magnetoplasma effects (helicon waves). However, at low temperatures (4 K), the transmitted radiation intensity shows magnetoquantum oscillations that represent the Shubnikov-de Haas effect at THz frequencies. At frequencies above 0.9 THz, when the radiation period is shorter than the Drude scattering time, an anomalously high transmission is observed in the magnetic quantum limit that can be interpreted as carrier localization at high frequencies.
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Affiliation(s)
- P Gogoi
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - D Kamenskyi
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
| | - D D Arslanov
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
| | - R T Jongma
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
| | - W J van der Zande
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
| | - B Redlich
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
| | - A F G van der Meer
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
| | - H Engelkamp
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - P C M Christianen
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - J C Maan
- High Field Magnet Laboratory (HFML-EMFL), Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
- FELIX Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
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Rikken RSM, Engelkamp H, Nolte RJM, Maan JC, van Hest JCM, Wilson DA, Christianen PCM. Shaping polymersomes into predictable morphologies via out-of-equilibrium self-assembly. Nat Commun 2016; 7:12606. [PMID: 27558520 PMCID: PMC5007325 DOI: 10.1038/ncomms12606] [Citation(s) in RCA: 110] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 07/18/2016] [Indexed: 02/08/2023] Open
Abstract
Polymersomes are bilayer vesicles, self-assembled from amphiphilic block copolymers. They are versatile nanocapsules with adjustable properties, such as flexibility, permeability, size and functionality. However, so far no methodological approach to control their shape exists. Here we demonstrate a mechanistically fully understood procedure to precisely control polymersome shape via an out-of-equilibrium process. Carefully selecting osmotic pressure and permeability initiates controlled deflation, resulting in transient capsule shapes, followed by reinflation of the polymersomes. The shape transformation towards stomatocytes, bowl-shaped vesicles, was probed with magnetic birefringence, permitting us to stop the process at any intermediate shape in the phase diagram. Quantitative electron microscopy analysis of the different morphologies reveals that this shape transformation proceeds via a long-predicted hysteretic deflation-inflation trajectory, which can be understood in terms of bending energy. Because of the high degree of controllability and predictability, this study provides the design rules for accessing polymersomes with all possible different shapes.
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Affiliation(s)
- R S M Rikken
- Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.,High Field Magnet Laboratory (HFML-EMFL), Radboud University Nijmegen, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - H Engelkamp
- Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.,High Field Magnet Laboratory (HFML-EMFL), Radboud University Nijmegen, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - R J M Nolte
- Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - J C Maan
- Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.,High Field Magnet Laboratory (HFML-EMFL), Radboud University Nijmegen, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - J C M van Hest
- Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - D A Wilson
- Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - P C M Christianen
- Institute for Molecules and Materials, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.,High Field Magnet Laboratory (HFML-EMFL), Radboud University Nijmegen, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
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Nagel U, Fishman RS, Katuwal T, Engelkamp H, Talbayev D, Yi HT, Cheong SW, Rõõm T. Terahertz spectroscopy of spin waves in multiferroic BiFeO3 in high magnetic fields. Phys Rev Lett 2013; 110:257201. [PMID: 23829754 DOI: 10.1103/physrevlett.110.257201] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Revised: 05/17/2013] [Indexed: 06/02/2023]
Abstract
We have studied the magnetic field dependence of far-infrared active magnetic modes in a single ferroelectric domain BiFeO3 crystal at low temperature. The modes soften close to the critical field of 18.8 T along the [001] (pseudocubic) axis, where the cycloidal structure changes to the homogeneous canted antiferromagnetic state and a new strong mode with linear field dependence appears that persists at least up to 31 T. A microscopic model that includes two Dzyaloshinskii-Moriya interactions and easy-axis anisotropy describes closely both the zero-field spectroscopic modes as well as their splitting and evolution in a magnetic field. The good agreement of theory with experiment suggests that the proposed model provides the foundation for future technological applications of this multiferroic material.
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Affiliation(s)
- U Nagel
- National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn, Estonia.
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Penc K, Romhányi J, Rõõm T, Nagel U, Antal A, Fehér T, Jánossy A, Engelkamp H, Murakawa H, Tokura Y, Szaller D, Bordács S, Kézsmárki I. Spin-stretching modes in anisotropic magnets: spin-wave excitations in the multiferroic Ba2CoGe2O7. Phys Rev Lett 2012; 108:257203. [PMID: 23004649 DOI: 10.1103/physrevlett.108.257203] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2012] [Indexed: 06/01/2023]
Abstract
We studied spin excitations in the magnetically ordered phase of the noncentrosymmetric Ba(2)CoGe(2)O(7) in high magnetic fields up to 33 T. In the electron spin resonance and far infrared absorption spectra we found several spin excitations beyond the two conventional magnon modes expected for such a two-sublattice antiferromagnet. We show that a multiboson spin-wave theory describes these unconventional modes, including spin-stretching modes, characterized by an oscillating magnetic dipole and quadrupole moment. The lack of inversion symmetry allows each mode to become electric dipole active. We expect that the spin-stretching modes can be generally observed in inelastic neutron scattering and light absorption experiments in a broad class of ordered S > 1/2 spin systems with strong single-ion anisotropy and/or noncentrosymmetric lattice structure.
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Affiliation(s)
- K Penc
- Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1525 Budapest, POB 49, Hungary
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Coolen HKAC, Engelkamp H, Reek JNH, Priem AH, Nolte RJM, van Leeuwen PWNM. Chiral basket-shaped host compounds derived from diphenylglycoluril. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/recl.19951140205] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Abstract
A disk-shaped molecule with chiral tails is shown to form long fibers of molecular diameter and micrometer length by self-assembly in chloroform. The molecules are derived from crown ethers and contain a phthalocyanine ring. In the fibers, they have a clockwise, staggered orientation that leads to an overall right-handed helical structure. These structures, in turn, self-assemble to form coiled-coil aggregates with left-handed helicity. Addition of potassium ions to the fibers leaves their structure intact but blocks the transfer of the chirality from the tails to the cores, leading to loss of the helicity of the fibers. These tunable chiral materials have potential in optoelectronic applications and as components in sensor devices.
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Affiliation(s)
- H Engelkamp
- Department of Organic Chemistry, NSR Center, University of Nijmegen, Toernooiveld, 6525 ED Nijmegen, Netherlands
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Adolph JMG, Engelkamp H, Herbig W, Peters PE, Wenzel-Hora BI. Iotrolan in urography: efficacy and tolerance in comparison with iohexol and iopamidol. Eur Radiol 1995. [DOI: 10.1007/bf02343264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Engelkamp H. Anwendung der Hartstrahltechnik (200 kV) bei Untersuchungen mit negativen Kontrastmitteln. ROFO-FORTSCHR RONTG 1960. [DOI: 10.1055/s-0029-1226617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Engelkamp H. Beitrag zu den Arthropathien bei Syringomyelie. ROFO-FORTSCHR RONTG 1956. [DOI: 10.1055/s-0029-1213029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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