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Title: Effects of aluminum substitution on the crystal structure and magnetic properties in Zn{sub 2}Y-type hexaferrites

Crystal structure and magnetic properties of multiferroic Y-type hexaferrites Ba{sub 0.5}Sr{sub 1.5}Zn{sub 2}(Fe{sub 1−x}Al{sub x}){sub 12}O{sub 22} (x = 0, 0.04, 0.08, and 0.12) were investigated. The Z- and M-type impurity phases decrease with increasing Al content, and the pure phase samples can be obtained by modulating Al-doping. Lattice distortion exists in Al-doped samples due to the different radius of Al ion (0.535 Å) and Fe ion (0.645 Å). The microstructural morphologies show that the hexagonal shape grains can be observed in all the samples, and grain size decreases with increasing Al content. As for magnetic properties of Ba{sub 0.5}Sr{sub 1.5}Zn{sub 2}(Fe{sub 1−x}Al{sub x}){sub 12}O{sub 22}, there exist rich thermal- and field-driven magnetic phase transitions. Temperature dependence of zero-field cooling magnetization curves from 5 K to 800 K exhibit three magnetic phase transitions involving conical spin phase, proper-screw spin phase, ferromagnetic phase, and paramagnetic phase, which can be found in all the samples. Furthermore, the phase-transition temperatures can be modulated by varying Al content. In addition, four kinds of typical hysteresis loops are observed in pure phase sample at different temperatures, which reveal different magnetization processes of above-motioned magnetic spin structures. Typically, triple hysteresis loops in low magnetic field range from 0 to 0.5 T can bemore » observed at 5 K, which suggests low-field driven magnetic phase transitions from conical spin order to proper-screw spin order and further to ferrimagnetic spin order occur. Furthermore, the coercive field (H{sub C}) and the saturation magnetization (M{sub S}) enhance with increasing Al content from x = 0 to 0.08, and drop rapidly at x = 0.12, which could be attribute to that in initial Al-doped process the pitch of spin helix increases and therefore magnetization enhances, but conical spin phase eventually collapses in higher-concentration Al-doping.« less
Authors:
; ; ; ; ; ;  [1] ;  [1] ;  [2]
  1. Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, 500 Dongchuan Rd., Shanghai 200241 (China)
  2. (China)
Publication Date:
OSTI Identifier:
22410111
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ALUMINIUM; ALUMINIUM IONS; BARIUM COMPOUNDS; CONCENTRATION RATIO; CRYSTAL STRUCTURE; DOPED MATERIALS; FERRITES; FERROMAGNETISM; GRAIN SIZE; HYSTERESIS; IRON IONS; MAGNETIC FIELDS; MAGNETIC PROPERTIES; MAGNETIZATION; PARAMAGNETISM; PHASE TRANSFORMATIONS; SPIN; STRONTIUM COMPOUNDS; TRANSITION TEMPERATURE; ZINC COMPOUNDS