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Your search keyword '"Circuits électroniques quantiques Alpes (QuantECA)"' showing total 8 results
Start Over Author "Circuits électroniques quantiques Alpes (QuantECA)" Journal journal of the american chemical society
8 results on '"Circuits électroniques quantiques Alpes (QuantECA)"'

1. A Stable Pentagonal Bipyramidal Dy(III) Single-Ion Magnet with a Record Magnetization Reversal Barrier over 1000 K

Author

Liviu Ungur, Veacheslav Vieru, Yan-Cong Chen, Jiang Liu, Ming-Liang Tong, Wolfgang Wernsdorfer, Jian-Hua Jia, Jun-Liang Liu, Yanhua Lan, Xiao-Ming Chen, Liviu F. Chibotaru, Song Gao, Institute for Infocomm Research - I²R [Singapore], Centre de Recherche Paul Pascal (CRPP), Université de Bordeaux (UB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institute for Nanoscale Physics and Chemistry (INPAC), Université Catholique de Louvain = Catholic University of Louvain (UCL), Division of Quantum and Chemistry, Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Institut für Anorganische Chemie, Geeorg-August Universität, Circuits électroniques quantiques Alpes (QuantECA ), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Norwegian University of Science and Technology [Trondheim] (NTNU), Norwegian University of Science and Technology (NTNU), Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry and Chemical Engineering, and Sun Yat-Sen University [Guangzhou] (SYSU)

Subjects
[PHYS]Physics [physics], Condensed matter physics, 010405 organic chemistry, Chemistry, Relaxation (NMR), General Chemistry, 010402 general chemistry, Magnetic hysteresis, 01 natural sciences, Biochemistry, Catalysis, 0104 chemical sciences, Magnetization, Magnetic anisotropy, Colloid and Surface Chemistry, Pentagonal bipyramidal molecular geometry, Excited state, Magnet, Anisotropy, ComputingMilieux_MISCELLANEOUS
Abstract

Single-molecule magnets (SMMs) with a large spin reversal barrier have been recognized to exhibit slow magnetic relaxation that can lead to a magnetic hysteresis loop. Synthesis of highly stable SMMs with both large energy barriers and significantly slow relaxation times is challenging. Here, we report two highly stable and neutral Dy(III) classical coordination compounds with pentagonal bipyramidal local geometry that exhibit SMM behavior. Weak intermolecular interactions in the undiluted single crystals are first observed for mononuclear lanthanide SMMs by micro-SQUID measurements. The investigation of magnetic relaxation reveals the thermally activated quantum tunneling of magnetization through the third excited Kramers doublet, owing to the increased axial magnetic anisotropy and weaker transverse magnetic anisotropy. As a result, pronounced magnetic hysteresis loops up to 14 K are observed, and the effective energy barrier (Ueff = 1025 K) for relaxation of magnetization reached a breakthrough among the SMMs.

Published
2016
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2. A Supramolecular Aggregate of Four Exchange-Biased Single-Molecule Magnets

Author

Khalil A. Abboud, George Christou, Tu N. Nguyen, Wolfgang Wernsdorfer, Circuits électroniques quantiques Alpes (QuantECA), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Department of Chemistry [Gainesville] (UF|Chemistry), and University of Florida [Gainesville] (UF)

Subjects
[PHYS]Physics [physics], 010405 organic chemistry, Chemistry, Supramolecular chemistry, General Chemistry, 010402 general chemistry, 01 natural sciences, Biochemistry, Magnetic susceptibility, Catalysis, 0104 chemical sciences, Magnetization, Crystallography, Hysteresis, Colloid and Surface Chemistry, Tetramer, Molecule, Ground state, Single crystal
Abstract

International audience; The reaction between 3-phenyl-1,5-bis(pyridin-2-yl)pentane-1,5-dione dioxime (pdpdH(2)) and triangular [Mn(3)(III)O(O(2)CMe)(py)(3)](ClO(4)) (1) affords [Mn(12)O(4)(O(2)CMe)(12)(pdpd)(6))](ClO(4))(4) (3). Complex 3 has a rectangular shape and consists of four [Mn(3)(III)O](7+) triangular units linked covalently by the dioximate ligands into a supramolecular [Mn(3)](4) tetramer. Solid-state dc and ac magnetic susceptibility measurements revealed that [Mn(3)](4) contains four Mn(3) single-molecule magnets (SMMs), each with an S = 6 ground state. Magnetization versus dc-field sweeps on a single crystal gave hysteresis loops below 1 K that exhibited exchange-biased quantum tunneling of magnetization steps, confirming 3 to be a supramolecular aggregate of four weakly exchange-coupled SMM units

Published
2011
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3. Strong axiality and Ising exchange interaction suppress zero-field tunneling of magnetization of an asymmetric Dy2 single-molecule magnet

Author

Yang Guo, Liviu F. Chibotaru, Liviu Ungur, Annie K. Powell, Hongjie Zhang, Yun-Nan Guo, Wolfgang Wernsdorfer, Jinkui Tang, Gong-Feng Xu, State Key Laboratory of Rare Resource Utilization, Changchun Institute of Applied Chemistry, Department of Chemistry, College of Science, Tianjin University of Commerce, Circuits électroniques quantiques Alpes (QuantECA), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Division of Quantum and Chemistry, Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Institut of Inorganic Chemistry, and University of Karlsruhe (TH)

Subjects
[PHYS]Physics [physics], Condensed matter physics, 010405 organic chemistry, Chemistry, Exchange interaction, Relaxation (NMR), General Chemistry, 010402 general chemistry, 01 natural sciences, Biochemistry, Catalysis, 0104 chemical sciences, Physics::Fluid Dynamics, Magnetization, Colloid and Surface Chemistry, Orders of magnitude (time), Ising model, Single-molecule magnet, Spin (physics), Axiality
Abstract

International audience; The high axiality and Ising exchange interaction efficiently suppress quantum tunneling of magnetization of an asymmetric dinuclear Dy-III complex, as revealed by combined experimental and theoretical investigations. Two distinct regimes of blockage of magnetization, one originating from the blockage at individual Dy sites and the other due to the exchange interaction between the sites, are separated for the first time. The latter contribution is found to be crucial, allowing an increase of the relaxation time by 3 orders of magnitude.

Published
2011
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4. The use of magnetic dilution to elucidate the slow magnetic relaxation effects of a Dy2 single-molecule magnet

Author

Muralee Murugesu, Ilia Korobkov, Jérôme Long, Wolfgang Wernsdorfer, Po-Heng Lin, Fatemah Habib, Chemistry Department, University of Ottawa, University of Ottawa [Ottawa], Centre for Catalysis Research and Innovation, Circuits électroniques quantiques Alpes (QuantECA), Institut Néel (NEEL), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)

Subjects
Condensed matter physics, 010405 organic chemistry, Chemistry, Relaxation (NMR), General Chemistry, 010402 general chemistry, 01 natural sciences, Biochemistry, Catalysis, 0104 chemical sciences, Ion, law.invention, SQUID, Magnetization, Colloid and Surface Chemistry, law, Condensed Matter::Superconductivity, Magnet, Diamagnetism, Single-molecule magnet, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Quantum tunnelling, ComputingMilieux_MISCELLANEOUS
Abstract

The magnetic dilution method was employed in order to elucidate the origin of the slow relaxation of the magnetization in a Dy(2) single-molecule magnet (SMM). The doping effect was studied using SQUID and micro-SQUID measurements on a Dy(2) SMM diluted in a diamagnetic Y(2) matrix. The quantum tunneling of the magnetization that can occur was suppressed by applying optimum dc fields. The dominant single-ion relaxation was found to be entangled with the neighboring Dy(III) ion relaxation within the molecule, greatly influencing the quantum tunneling of the magnetization in this complex.

Published
2011
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5. Single-molecule magnet behavior for an antiferromagnetically superexchange-coupled dinuclear dysprosium(III) complex

Author

Gary D. Enright, Muralee Murugesu, Wolfgang Wernsdorfer, Liviu F. Chibotaru, Liviu Ungur, Po-Heng Lin, Jérôme Long, Ilia Korobkov, Fatemah Habib, Chemistry Department, University of Ottawa, University of Ottawa [Ottawa], Centre for Catalysis Research and Innovation, Institute for nanoscale physics and chemistry, Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Circuits électroniques quantiques Alpes (QuantECA), Institut Néel (NEEL), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)

Subjects
Lanthanide, 010405 organic chemistry, Inorganic chemistry, Relaxation (NMR), chemistry.chemical_element, General Chemistry, 010402 general chemistry, 01 natural sciences, Biochemistry, Catalysis, 3. Good health, 0104 chemical sciences, Magnetization, Crystallography, Colloid and Surface Chemistry, chemistry, Ab initio quantum chemistry methods, Superexchange, Dysprosium, Antiferromagnetism, Single-molecule magnet, [CHIM.COOR]Chemical Sciences/Coordination chemistry, ComputingMilieux_MISCELLANEOUS
Abstract

A family of five dinuclear lanthanide complexes has been synthesized with general formula [Ln(III)(2)(valdien)(2)(NO(3))(2)] where (H(2)valdien = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine) and Ln(III) = Eu(III)1, Gd(III)2, Tb(III)3, Dy(III)4, and Ho(III)5. The magnetic investigations reveal that 4 exhibits single-molecule magnet (SMM) behavior with an anisotropic barrier U(eff) = 76 K. The step-like features in the hysteresis loops observed for 4 reveal an antiferromagnetic exchange coupling between the two dysprosium ions. Ab initio calculations confirm the weak antiferromagnetic interaction with an exchange constant J(Dy-Dy) = -0.21 cm(-1). The observed steps in the hysteresis loops correspond to a weakly coupled system similar to exchange-biased SMMs. The Dy(2) complex is an ideal candidate for the elucidation of slow relaxation of the magnetization mechanism seen in lanthanide systems.

Published
2011
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6. Electro-oxidized epitaxial graphene channel field-effect transistors with single-walled carbon nanotube thin film gate electrode

Author

Feihu Wang, Palanisamy Ramesh, Robert C. Haddon, Sandip Niyogi, Xiaoliu Chi, Claire Berger, Mikhail E. Itkis, Walt de Heer, Elena Bekyarova, Center for Nanoscale Science and Engineering [Riverside], University of California [Riverside] (UCR), University of California-University of California, Circuits électroniques quantiques Alpes (QuantECA), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), School of Physics, and Georgia Institute of Technology [Atlanta]

Subjects
Nanotechnology, 02 engineering and technology, Carbon nanotube, 010402 general chemistry, 7. Clean energy, 01 natural sciences, Biochemistry, Catalysis, law.invention, symbols.namesake, Colloid and Surface Chemistry, law, Graphite, Thin film, [PHYS.COND.CM-MSQHE]Physics [physics]/Condensed Matter [cond-mat]/Mesoscopic Systems and Quantum Hall Effect [cond-mat.mes-hall], Graphene oxide paper, Chemistry, Graphene, business.industry, Fermi level, General Chemistry, 021001 nanoscience & nanotechnology, 0104 chemical sciences, symbols, Optoelectronics, Field-effect transistor, 0210 nano-technology, business, Graphene nanoribbons
Abstract

International audience; We report the effect of electrochemical oxidation in nitric acid on the electronic properties of epitaxial graphene (EG) grown on silicon carbide substrates; we demonstrate the availability of an additional reaction channel in EG, which is not present in graphite but which facilitates the introduction of the reaction medium into the graphene galleries during electro-oxidation. The device performance of the chemically processed graphene was studied by patterning the EG wafers with two geometrically identical macroscopic channels; the electro-oxidized channel showed a logarithmic increase of resistance with decreasing temperature, which is ascribed to the scattering of charge carriers in a two-dimensional electronic gas, rather than the presence of an energy gap at the Fermi level. Field-effect transistors were fabricated on the electro-oxidized and pristine graphene channels using single-walled carbon nanotube thin film top gate electrodes, thereby allowing the study of the effect of oxidative chemistry on the transistor performance of EG. The electro-oxidized channel showed higher values for the on-off ratio and the mobility of the graphene field-effect transistor, which we ascribe to the availability of high-quality internal graphene layers after electro-oxidation of the more defective top layers. Thus, the present oxidative process provides a clear contrast with previously demonstrated covalent chemistry in which sp3 hybridized carbon atoms are introduced into the graphitic transport layer of the lattice by carbon-carbon bond formation, thereby opening an energy gap.

Published
2010
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7. Anchoring of Rare-Earth-Based Single-Molecule Magnets on Single-Walled Carbon Nanotubes

Author

Mario Ruben, Lapo Bogani, Frank Hennrich, Wolfgang Wernsdorfer, Manfred M. Kappes, Svetlana Kyatskaya, José Ramón Galán Mascarós, 1. Physikalisches Institut [Stuttgart], Universität Stuttgart [Stuttgart], Circuits électroniques quantiques Alpes (QuantECA), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), and Karlsruhe Institute of Technology (KIT)

Subjects
Supramolecular chemistry, chemistry.chemical_element, Nanotechnology, Terbium, 02 engineering and technology, Carbon nanotube, 010402 general chemistry, 01 natural sciences, Biochemistry, Catalysis, law.invention, Colloid and Surface Chemistry, law, [PHYS]Physics [physics], Spintronics, Chemistry, Intermolecular force, Force spectroscopy, General Chemistry, 021001 nanoscience & nanotechnology, equipment and supplies, Magnetic susceptibility, 0104 chemical sciences, Chemical physics, 0210 nano-technology, human activities, Conjugate
Abstract

International audience; A new heteroleptic bis(phthalocyaninato)terbium(III) complex 1, bearing a pyrenyl group, exhibits temperature and frequency dependence of ac magnetic susceptibility, typical of single-molecule magnets. The complex was successfully attached to single-walled carbon nanotubes (SWNTs) using pi-pi interactions, yielding a 1-SWNT conjugate. The supramolecular grafting of 1 to SWNTs was proven qualitatively and quantitatively by high-resolution transmission electron microscopy, emission spectroscopy, and atomic force spectroscopy. Giving a clear magnetic fingerprint, the anisotropy energy barrier and the magnetic relaxation time of the 1-SWNT conjugate are both increased in comparison with the pure crystalline compound 1, likely due to the suppression of intermolecular interactions. The obtained results propose the 1-SWNT conjugate as a promising constituent unit in magnetic single-molecule measurements using molecular spintronics devices.

Published
2009
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8. Photoinduced superparamagnetism in trimetallic coordination nanoparticles

Author

Corine Mathonière, Talal Mallah, Laure Catala, Alexandre Gloter, Daniela Brinzei, Odile Stéphan, Wolfgang Wernsdorfer, Institut de Chimie Moléculaire et des Matériaux d'Orsay (ICMMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université de Bordeaux (UB), Circuits électroniques quantiques Alpes (QuantECA), Institut Néel (NEEL), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Solides (LPS), and Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)

Subjects
Chemistry, Relaxation (NMR), Nanoparticle, Superparamagnetism, Nanotechnology, Coordination network, 02 engineering and technology, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, Photochemistry, Photomagnetism, 01 natural sciences, Biochemistry, Catalysis, 0104 chemical sciences, Electron transfer, Colloid and Surface Chemistry, Nanoparticles, 0210 nano-technology
Abstract

Trimetallic CuNiMo(CN)8 coordination nanoparticles with a narrow size distribution around 3 nm were obtained. A photoinduced superparamagnetic behavior was evidenced at low temperature by microSQUID studies. The relaxation studies reveal a behavior similar to that observed for single-molecule magnets (SMMs).

Published
2007
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