Abstract

A spin glass state is observed in the double perovskite oxide Sr2FeCoO6 prepared through sol-gel technique. Initial structural studies using x rays reveal that the compound crystallizes in tetragonal I4/m structure with lattice parameters, a 5.4609(2) Å and c 7.7113(7) Å. the temperature dependent powder x ray diffraction data reveal no structural phase transition in the temperature range 10-300 K. However, the unit cell volume shows an anomaly coinciding with the magnetic transition temperature thereby suggesting a close connection between lattice and magnetism. Neutron diffraction studies and subsequent bond valence sums analysis show that in Sr2FeCoO6, the B site is randomly occupied by Fe and Co in the mixed valence states of Fe3+/Fe4+ and Co3+/Co4+. the random occupancy and mixed valence set the stage for inhomogeneous magnetic exchange interactions and in turn, for the spin glass state in this double perovskite, which is observed as an irreversibility in temperature dependent dc magnetization at T f ∼ 75 K. Dynamical scaling analysis of ′(T) yields a critical temperature T ct 75.14(8) K and an exponent z 6.2(2) typical for spin glasses. the signature of presence of mixed magnetic interactions is obtained from the thermal hysteresis in magnetization of Sr2FeCoO6. Combining the neutron and magnetization results of Sr2FeCoO6, we deduce that Fe is in low spin state while Co is in both low spin and intermediate spin states. © 2012 American Institute of Physics.

Department(s)

Physics

Publication Status

Available Access

Comments

Department of Science and Technology, Ministry of Science and Technology, India, Grant SR/FST/PSII-002/2007

International Standard Serial Number (ISSN)

0021-8979

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2024 American Institute of Physics, All rights reserved.

Publication Date

01 Mar 2012

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