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Title: Magnetic Behaviour of Layered Ag(ll) Fluorides

Abstract

Fluoride phases that contain the spin-1/2 4d{sup 9} Ag(II) ion have recently been predicted to have interesting or unusual magnetochemistry, owing to their structural similarity to the 3d{sup 9} Cu(II) cuprates and the covalence associated with this unusual oxidation state of silver. Here we present a comprehensive study of structure and magnetism in the layered Ag(II) fluoride Cs{sub 2}AgF{sub 4}, using magnetic susceptometry, inelastic neutron scattering techniques and both X-ray and neutron powder diffraction. We find that this material is well described as a two-dimensional ferromagnet, in sharp contrast to the high-T{sub c} cuprates and a previous report in the literature. Analyses of the structural data show that Cs{sub 2}AgF{sub 4} is orbitally ordered at all temperatures of measurement. Therefore, we suggest that orbital ordering may be the origin of the ferromagnetism we observe in this material.

Authors:
 [1];  [1];  [2];  [3];  [4];  [5];  [1];  [6]
  1. ORNL
  2. University of St. Andrews, Scotland
  3. University of Tennessee, Knoxville (UTK)
  4. {F E } [ORNL
  5. Los Alamos National Laboratory (LANL)
  6. ISIS Facility, Rutherford Appleton Laboratory
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
978207
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature Materials; Journal Volume: 5
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; COVALENCE; CUPRATES; DIFFRACTION; FERROMAGNETISM; FLUORIDES; MAGNETISM; NEUTRONS; ORIGIN; SCATTERING; SILVER; VALENCE

Citation Formats

McLain, Sylvia E, Dolgos, Michelle R, Tennant, D. A., Turner, John F. C., Barnes, Ted, Proffen, Th., Sales, Brian C, and Bewley, Robert I. Magnetic Behaviour of Layered Ag(ll) Fluorides. United States: N. p., 2006. Web. doi:10.1038/nmat1670.
McLain, Sylvia E, Dolgos, Michelle R, Tennant, D. A., Turner, John F. C., Barnes, Ted, Proffen, Th., Sales, Brian C, & Bewley, Robert I. Magnetic Behaviour of Layered Ag(ll) Fluorides. United States. doi:10.1038/nmat1670.
McLain, Sylvia E, Dolgos, Michelle R, Tennant, D. A., Turner, John F. C., Barnes, Ted, Proffen, Th., Sales, Brian C, and Bewley, Robert I. Sun . "Magnetic Behaviour of Layered Ag(ll) Fluorides". United States. doi:10.1038/nmat1670.
@article{osti_978207,
title = {Magnetic Behaviour of Layered Ag(ll) Fluorides},
author = {McLain, Sylvia E and Dolgos, Michelle R and Tennant, D. A. and Turner, John F. C. and Barnes, Ted and Proffen, Th. and Sales, Brian C and Bewley, Robert I.},
abstractNote = {Fluoride phases that contain the spin-1/2 4d{sup 9} Ag(II) ion have recently been predicted to have interesting or unusual magnetochemistry, owing to their structural similarity to the 3d{sup 9} Cu(II) cuprates and the covalence associated with this unusual oxidation state of silver. Here we present a comprehensive study of structure and magnetism in the layered Ag(II) fluoride Cs{sub 2}AgF{sub 4}, using magnetic susceptometry, inelastic neutron scattering techniques and both X-ray and neutron powder diffraction. We find that this material is well described as a two-dimensional ferromagnet, in sharp contrast to the high-T{sub c} cuprates and a previous report in the literature. Analyses of the structural data show that Cs{sub 2}AgF{sub 4} is orbitally ordered at all temperatures of measurement. Therefore, we suggest that orbital ordering may be the origin of the ferromagnetism we observe in this material.},
doi = {10.1038/nmat1670},
journal = {Nature Materials},
number = ,
volume = 5,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • Fluoride phases that contain the spin-1/2 4d{sup 9} Ag(II) ion have recently been predicted to have interesting or unusual magnetochemistry, owing to their structural similarity to the 3d{sup 9} Cu(II) cuprates and the covalence associated with this unusual oxidation state of silver. Here we present a comprehensive study of structure and magnetism in the layered Ag(II) fluoride Cs{sub 2}AgF{sub 4}, using magnetic susceptometry, inelastic neutron scattering techniques and both X-ray and neutron powder diffraction. We find that this material is well described as a two-dimensional ferromagnet, in sharp contrast to the high-T{sub C} cuprates and a previous report in themore » literature. Analyses of the structural data show that Cs{sub 2}AgF{sub 4} is orbitally ordered at all temperatures of measurement. Therefore, we suggest that orbital ordering may be the origin of the ferromagnetism we observe in this material.« less
  • The lanthanide coinage-metal diarsenides LnTAs{sub 2} (Ln=La, Ce-Nd, Sm; T=Ag, Au) have been reinvestigated and their structures have been refined from single crystal X-ray data. Two different distortion variants of the HfCuSi{sub 2} type are found: PrAgAs{sub 2}, NdAgAs{sub 2}, SmAgAs{sub 2}, GdAgAs{sub 2}, TbAgAs{sub 2}, NdAuAs{sub 2} and SmAuAs{sub 2} crystallize as twofold superstructures in space group Pmcn with the As atoms of their planar layers forming zigzag chains, whereas LaAgAs{sub 2}, CeAgAs{sub 2} and PrAuAs{sub 2} adopt a fourfold superstructure (space group Pmca) with cis-trans chains of As atoms. The respective atomic positions can be derived from themore » HfCuSi{sub 2} type by group-subgroup relations. The compounds with zigzag chains of As atoms exhibit metallic behaviour while those with cis-trans chains are semiconducting as measured on powder pellets. The majority of the compounds including 4f elements show antiferromagnetic ordering at T{sub N}<20 K. - Text3: Zigzig vs. cis-trans.« less
  • The synthesis of a high-purity sample of the layered oxide selenide Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} is reported. At ambient temperature it crystallises in the space group I4/mmm with two formula units in the unit cell and lattice parameters a=4.08771(1) Å, c=19.13087(8) Å. The compound displays mixed-valent manganese in a formal oxidation state close to +2.5 and powder neutron diffraction measurements reveal that below the Néel temperature of 63(1) K this results in an antiferromagnetic structure which may be described as A-type, modelled in the magnetic space group P{sub I}4/mnc (128.410 in the Belov, Neronova and Smirnova (BNS) scheme) inmore » which localised Mn moments of 3.99(2) μ{sub B} are arranged in ferromagnetic layers which are coupled antiferromagnetically. In contrast to the isostructural compound Sr{sub 2}MnO{sub 2}Cu{sub 1.5}S{sub 2}, Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} does not display long range ordering of coinage metal ions and vacancies, nor may significant amounts of the coinage metal readily be deintercalated using soft chemical methods. - Graphical abstract: Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} containing mixed valent Mn ions undergoes magnetic ordering with ferromagnetic coupling within MnO{sub 2} sheets and antiferromagnetic coupling between MnO{sub 2} sheets. - Highlights: • High purity sample of Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} obtained. • Magnetic structure determined. • Compared with related mixed-valent manganite oxide chalcogenides.« less
  • No abstract prepared.