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Title: Lifting the geometric frustration through a monoclinic distortion in “114” YBaFe{sub 4}O{sub 7.0}: Magnetism and transport

The possibility to lift the geometric frustration in the “114” stoichiomeric tetragonal oxide YBaFe{sub 4}O{sub 7.0} by decreasing the temperature has been investigated using neutron and synchrotron powder diffraction techniques. Besides the structural transition from tetragonal to monoclinic symmetry that appears at T{sub S}=180 K, a magnetic transition is observed below T{sub N}=95 K. The latter corresponds to a lifting of the 3D geometric frustration toward an antiferromagnetic long range ordering, never observed to date in a cubic based “114’” oxide. The magnetic structure, characterized by the propagation vector k{sub 1}=(0,0,½), shows that one iron Fe2 exhibits a larger magnetic moment than the three others, suggesting a possible charge ordering according to the formula YBaFe{sup 3+}Fe{sub 3}{sup 2+}O{sub 7.0}. The magnetic M(T) and χ′(T) curves, in agreement with neutron data, confirm the structural and magnetic transitions and evidence the coexistence of residual magnetic frustration. Moreover, the transport measurements show a resistive transition from a thermally activated conduction mechanism to a variable range hopping mechanism at T{sub S}=180 K, with a significant increase of the dependence of the resistivity vs. temperature. Mössbauer spectroscopy clearly evidences a change in the electronic configuration of the iron framework at the structural transition as wellmore » as coexistence of several oxidation states. The role of barium underbonding in these transitions is discussed. - Graphical abstract: Atomic displacements at the tetragonal-monoclinic transition in YBaFe{sub 4}O{sub 7}. Display Omitted - Highlights: • The structural and magnetic phase transitions of YBaFe{sub 4}O{sub 7} were studied below room temperature. • The tetragonal to monoclinic transition, characterized by NPD and SXRD, was studied using mode crystallography approach. • Monoclinic distortion allows the lifting of the geometrical frustration on the iron sublattice, leading to AF order at T=95 K.« less
Authors:
;  [1] ;  [1] ; ;  [1] ;  [2] ;  [3] ; ;  [4]
  1. CRISMAT, CNRS-ENSICAEN, 6 Bd Marechal Juin, 14050 Caen (France)
  2. Bragg Institute, Australian Nuclear Science and Technology Organization, PMB 1, Menai, NSW 2234 (Australia)
  3. Paul Scherrer Institute, Swiss Light Source, CH-5232 Villigen (Switzerland)
  4. UCQR, IST/ITN, Instituto Superior Técnico, Universidade Técnica de Lisboa, CFMC-UL, 2686-953 Sacavém (Portugal)
Publication Date:
OSTI Identifier:
22274095
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 205; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; ANTIFERROMAGNETISM; ATOMIC DISPLACEMENTS; CRYSTALLOGRAPHY; DIFFRACTION; ELECTRONIC STRUCTURE; IRON; IRON OXIDES; MAGNETIC MOMENTS; MONOCLINIC LATTICES; NEUTRONS; PHASE TRANSFORMATIONS; POWDERS; SPECTROSCOPY