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Title: Magnetic properties and hyperfine interactions in Cr{sub 8}, Cr{sub 7}Cd, and Cr{sub 7}Ni molecular rings from {sup 19}F-NMR

A detailed experimental investigation of the {sup 19}F nuclear magnetic resonance is made on single crystals of the homometallic Cr{sub 8} antiferromagnetic molecular ring and heterometallic Cr{sub 7}Cd and Cr{sub 7}Ni rings in the low temperature ground state. Since the F{sup −} ion is located midway between neighboring magnetic metal ions in the ring, the {sup 19}F-NMR spectra yield information about the local electronic spin density and {sup 19}F hyperfine interactions. In Cr{sub 8}, where the ground state is a singlet with total spin S{sub T} = 0, the {sup 19}F-NMR spectra at 1.7 K and low external magnetic field display a single narrow line, while when the magnetic field is increased towards the first level crossing field, satellite lines appear in the {sup 19}F-NMR spectrum, indicating a progressive increase in the Boltzmann population of the first excited state S{sub T} = 1. In the heterometallic rings, Cr{sub 7}Cd and Cr{sub 7}Ni, whose ground state is magnetic with S{sub T} = 3/2 and S{sub T} = 1/2, respectively, the {sup 19}F-NMR spectrum has a complicated structure which depends on the strength and orientation of the magnetic field, due to both isotropic and anisotropic transferred hyperfine interactions and classical dipolar interactions.more » From the {sup 19}F-NMR spectra in single crystals we estimated the transferred hyperfine constants for both the F{sup −}-Ni{sup 2+} and the F{sup −}-Cd{sup 2+} bonds. The values of the hyperfine constants compare well to the ones known for F{sup −}-Ni{sup 2+} in KNiF{sub 3} and NiF{sub 2} and for F{sup −}-Cr{sup 3+} in K{sub 2}NaCrF{sub 6}. The results are discussed in terms of hybridization of the 2s, 2p orbitals of the F{sup −} ion and the d orbitals of the magnetic ion. Finally, we discuss the implications of our results for the electron-spin decoherence.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [4] ;  [2] ;  [1] ;  [3] ;  [5] ;  [1] ;  [2] ;  [2] ;  [6] ;  [7] ; ;  [8]
  1. Department of Physics, Università di Pavia, I-27100 Pavia (Italy)
  2. (Italy)
  3. (United States)
  4. Department of Physics, Università degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy)
  5. Department of Physics and Astronomy, Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States)
  6. Dipartimento di Fisica e Scienze della Terra, Università di Parma, Viale G. P. Usberti 7/A, 43124 Parma (Italy)
  7. S3 Istituto Nanoscienze, Consiglio Nazionale delle Ricerche, I-4100 Modena (Italy)
  8. The Lewis Magnetism Laboratory, The University of Manchester, M13 9PL Manchester (United Kingdom)
Publication Date:
OSTI Identifier:
22253245
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 140; Journal Issue: 14; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANISOTROPY; ANTIFERROMAGNETISM; CADMIUM IONS; CHROMIUM IONS; DENSITY; EXCITED STATES; FLUORINE 19; GROUND STATES; HYBRIDIZATION; INTERACTIONS; MAGNETIC FIELDS; MAGNETIC PROPERTIES; MONOCRYSTALS; NICKEL FLUORIDES; NICKEL IONS; NMR SPECTRA; NUCLEAR MAGNETIC RESONANCE; SATELLITES