Low temperature magnetic properties and spin dynamics in single crystals of Cr8Zn antiferromagnetic molecular rings

Autor: Alessandro Chiesa, Richard E. P. Winpenny, Stefano Carretta, Grigore A. Timco, Ferdinando Borsa, Christian Cervetti, Marco Evangelisti, Ilya Sheikin, Alberto Ghirri, Andrea Candini, Alessandro Lascialfari, S. Bordignon, Fatemeh Adelnia, Marco Affronte
Přispěvatelé: Ministero dell'Istruzione, dell'Università e della Ricerca, INFM and Dipartimento di Fisica, University of Parma = Università degli studi di Parma [Parme, Italie], Instituto de Ciencia de Materiales de Aragón [Saragoza, España] (ICMA-CSIC), University of Zaragoza - Universidad de Zaragoza [Zaragoza], CNR-INFM and Dipartimento di Fisica, Università di Modena e Reggio Emilia, CNR-INFM and Dipartimento di Fisica, Laboratoire national des champs magnétiques intenses - Grenoble (LNCMI-G), Université Joseph Fourier - Grenoble 1 (UJF)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Milano [Milano] (UNIMI)
Rok vydání: 2015
Předmět:
Zdroj: Journal of Chemical Physics
Journal of Chemical Physics, American Institute of Physics, 2015, 143 (24), pp.244321. ⟨10.1063/1.4938086⟩
Digital.CSIC. Repositorio Institucional del CSIC
instname
The Journal of chemical physics 143 (2015). doi:10.1063/1.4938086
info:cnr-pdr/source/autori:Adelnia F.; Chiesa A.; Bordignon S.; Carretta S.; Ghirri A.; Candini A.; Cervetti C.; Evangelisti M.; Affronte M.; Sheikin I.; Winpenny R.; Timco G.; Borsa F.; Lascialfari A./titolo:Low temperature magnetic properties and spin dynamics in single crystals of Cr8Zn antiferromagnetic molecular rings/doi:10.1063%2F1.4938086/rivista:The Journal of chemical physics/anno:2015/pagina_da:/pagina_a:/intervallo_pagine:/volume:143
ISSN: 0021-9606
1089-7690
Popis: Under the terms of the CC BY license.-- et al.
A detailed experimental investigation of the effects giving rise to the magnetic energy level structure in the vicinity of the level crossing (LC) at low temperature is reported for the open antiferromagnetic molecular ring CrZn. The study is conducted by means of thermodynamic techniques (torque magnetometry, magnetization and specific heat measurements) and microscopic techniques (nuclear magnetic resonance line width, nuclear spin lattice, and spin-spin relaxation measurements). The experimental results are shown to be in excellent agreement with theoretical calculations based on a minimal spin model Hamiltonian, which includes a Dzyaloshinskii-Moriya interaction. The first ground state level crossing at μH = 2.15 T is found to be an almost true LC while the second LC at μH = 6.95 T has an anti-crossing gap of Δ = 0.19 K. In addition, both NMR and specific heat measurements show the presence of a level anti-crossing between excited states at μH = 4.5 T as predicted by the theory. In all cases, the fit of the experimental data is improved by introducing a distribution of the isotropic exchange couplings (J), i.e., using a J strain model. The peaks at the first and second LCs in the nuclear spin-lattice relaxation rate are dominated by inelastic scattering and a value of Γ ∼ 10 rad/s is inferred for the life time broadening of the excited state of the open ring, due to spin phonon interaction. A loss of NMR signal (wipe-out effect) is observed for the first time at LC and is explained by the enhancement of the spin-spin relaxation rate due to the inelastic scattering.
This work was financially supported by the Italian FIRB Project No. RBFR12RPD1 of the Italian MIUR “New Challenges in Molecular Nanomagnetism: From Spin Dynamics to Quantum-Information Processing.”
Databáze: OpenAIRE
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