The effect of A-site substitution on the structure and magnetism of Sr2-xPrxFeCoO6 (x = 0, 1, 2)
01 May 2018-Vol. 1953, Iss: 1, pp 120053
About: The article was published on 2018-05-01. It has received None citations till now. The article focuses on the topics: Substitution (logic).
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TL;DR: VESTA has been upgraded to the latest version, VESTA 3, implementing new features including drawing the external morphology of crystals, and an extended bond-search algorithm to enable more sophisticated searches in complex molecules and cage-like structures.
Abstract: VESTA is a three-dimensional visualization system for crystallographic studies and electronic state calculations. It has been upgraded to the latest version, VESTA 3, implementing new features including drawing the external morphology of crystals; superimposing multiple structural models, volumetric data and crystal faces; calculation of electron and nuclear densities from structure parameters; calculation of Patterson functions from structure parameters or volumetric data; integration of electron and nuclear densities by Voronoi tessellation; visualization of isosurfaces with multiple levels; determination of the best plane for selected atoms; an extended bond-search algorithm to enable more sophisticated searches in complex molecules and cage-like structures; undo and redo in graphical user interface operations; and significant performance improvements in rendering isosurfaces and calculating slices.
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TL;DR: The use of neutrons for the determination of magnetic structures has been a hot topic in the last 15 years as discussed by the authors, where the knowledge of the magnetism is a prerequisite for understanding the underlying functional mechanisms.
Abstract: In 1949 Shull et al. [1] used for the first time neutrons for the determination of a magnetic structure. Ever since, the need for neutrons for the study of magnetism has increased. Two main reasons can be brought forward to explain this ongoing success: First of all a strong rise in research on functional materials (founding obliges) and secondly the increasing availability of easy to use programmes for the treatment of magnetic neutron diffraction data. The giant magnetoresistance effect, multiferroic materials, magnetoelasticity, magnetic shape memory alloys, magnetocaloric materials, high temperature superconductivity or spin polarized half metals: The last 15 years have seen the event of all these “hot topics” where the knowledge of the magnetism is a prerequisite for understanding the underlying functional mechanisms. Refinement programs like FULLPROF or GSAS and programs for magnetic symmetry analysis like BASIREPS or SARAH make the determination of magnetic structures accessible for non specialists. Following a historical overview on the use of neutron powder diffraction for the determination of magnetic structures, I will try to convince you of the easiness of using magnetic symmetry analysis for the determination of magnetic structures using some recent examples of own research on the rare earth iron borate TbFe3(BO3)4 and the rare earth transition metal telluride Ho6FeTe2.
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TL;DR: In this paper, a spin glass state is observed in the double perovskite oxide Sr2FeCoO6 prepared through sol-gel technique, which shows that the compound crystallizes in tetragonal I4/m structure with lattice parameters.
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) A and c = 7.7113(7) A. 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 sets 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 Tf ∼ 75 K. Dynamical scaling analysis of χ′(T) yields a critical temperature Tct = 75.14(8) K and an exponent zν = 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.
49 citations
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TL;DR: In this paper, the exchange bias and memory effect in double perovskite Sr2FeCoO6 was observed and the spin glass transition temperature, Tg, versus Hdc2/3, followed the Almeida-Thouless line yielding a freezing temperature of Tf=73K.
Abstract: We report on the observation of exchange bias (EB) and memory effect in double perovskite Sr2FeCoO6. Antiphase boundaries between the ferromagnetic and the antiferromagnetic regions in the disordered glassy phase are assumed as responsible for the observed effect, which reflects in the cooling field dependence and temperature evolution of exchange bias field and in training effect. The spin glass (SG) phase itself is characterized through memory, ageing, and magnetic relaxation experiments. The spin glass transition temperature, Tg, versus Hdc2/3 follows the Almeida-Thouless line yielding a freezing temperature, Tf=73K. Time-dependent magnetic relaxation studies reveal the magnetization dynamics of the underlying glassy phase in this double perovskite.
42 citations
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TL;DR: In this paper, the exchange bias and memory effect in double perovskite was observed and the spin glass transition temperature was characterized through memory, ageing and magnetic relaxation experiments, which reflected in the cooling field dependence and temperature evolution of exchange bias field and in training effect.
Abstract: We report on the observation of exchange bias and memory effect in double perovskite Sr$_2$FeCoO$_6$. Antiphase boundaries between the ferromagnetic and antiferromagnetic regions in the disordered glassy phase is assumed as responsible for the observed effect which reflects in the cooling field dependence and temperature evolution of exchange bias field and in training effect. The spin glass phase itself is characterized through memory, ageing and magnetic relaxation experiments. The spin glass transition temperature, $T_g$, versus $H_{dc}^{2/3}$ follows the Almeida-Thouless line yielding a freezing temperature, $T_f$ = 73 K. Time-dependent magnetic relaxation studies reveal the magnetization dynamics of the underlying glassy phase in this double perovskite.
37 citations
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