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Title: Thermally assisted interlayer magnetic coupling through Ba{sub 0.05}Sr{sub 0.95}TiO{sub 3} barriers

Abstract

We report on the interlayer exchange coupling across insulating barriers observed on Ni{sub 80}Fe{sub 20}/Ba{sub 0.05}Sr{sub 0.95}TiO{sub 3}/La{sub 0.66}Sr{sub 0.33}MnO{sub 3} (Py/BST{sub 0.05}/LSMO) trilayers. The coupling mechanism has been analyzed in terms of the barrier thickness, samples' substrate, and temperature. We examined the effect of MgO (MGO) and SrTiO{sub 3} (STO) (001) single-crystalline substrates on the magnetic coupling and also on the magnetic anisotropies of the samples in order to get a deeper understanding of the magnetism of the structures. We measured a weak coupling mediated by spin-dependent tunneling phenomena whose sign and strength depend on barrier thickness and substrate. An antiferromagnetic (AF) exchange prevails for most of the samples and smoothly increases with the barrier thicknesses as a consequence of the screening effects of the BST{sub 0.05}. The coupling monotonically increases with temperature in all the samples and this behavior is attributed to thermally assisted mechanisms. The magnetic anisotropy of both magnetic components has a cubic symmetry that in the case of permalloy is added to a small uniaxial component.

Authors:
;  [1];  [2]; ;  [3];  [2];  [3];  [2];  [2]
  1. Centro Atómico Constituyentes, San Martín, Buenos Aires 1650 (Argentina)
  2. (Argentina)
  3. Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autonoma de Buenos Aires C1425FQB (Argentina)
Publication Date:
OSTI Identifier:
22594350
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 109; Journal Issue: 6; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; ANTIFERROMAGNETISM; BARIUM COMPOUNDS; COUPLING; MAGNESIUM OXIDES; MONOCRYSTALS; PERMALLOY; SCREENING; SPIN; STRONTIUM TITANATES; SUBSTRATES; SYMMETRY; THICKNESS; TUNNEL EFFECT

Citation Formats

Carreira, Santiago J., Steren, Laura B., Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autonoma de Buenos Aires C1425FQB, Avilés Félix, Luis, Alejandro, Gabriela, Centro Atómico Bariloche, Bariloche, Rio Negro 8400, Sirena, Martín, Centro Atómico Bariloche, Bariloche, Rio Negro 8400, and Instituto Balseiro-CNEA & Univ. Nac. de Cuyo, Bariloche, Rio Negro 8400. Thermally assisted interlayer magnetic coupling through Ba{sub 0.05}Sr{sub 0.95}TiO{sub 3} barriers. United States: N. p., 2016. Web. doi:10.1063/1.4960639.
Carreira, Santiago J., Steren, Laura B., Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autonoma de Buenos Aires C1425FQB, Avilés Félix, Luis, Alejandro, Gabriela, Centro Atómico Bariloche, Bariloche, Rio Negro 8400, Sirena, Martín, Centro Atómico Bariloche, Bariloche, Rio Negro 8400, & Instituto Balseiro-CNEA & Univ. Nac. de Cuyo, Bariloche, Rio Negro 8400. Thermally assisted interlayer magnetic coupling through Ba{sub 0.05}Sr{sub 0.95}TiO{sub 3} barriers. United States. doi:10.1063/1.4960639.
Carreira, Santiago J., Steren, Laura B., Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autonoma de Buenos Aires C1425FQB, Avilés Félix, Luis, Alejandro, Gabriela, Centro Atómico Bariloche, Bariloche, Rio Negro 8400, Sirena, Martín, Centro Atómico Bariloche, Bariloche, Rio Negro 8400, and Instituto Balseiro-CNEA & Univ. Nac. de Cuyo, Bariloche, Rio Negro 8400. Mon . "Thermally assisted interlayer magnetic coupling through Ba{sub 0.05}Sr{sub 0.95}TiO{sub 3} barriers". United States. doi:10.1063/1.4960639.
@article{osti_22594350,
title = {Thermally assisted interlayer magnetic coupling through Ba{sub 0.05}Sr{sub 0.95}TiO{sub 3} barriers},
author = {Carreira, Santiago J. and Steren, Laura B. and Consejo Nacional de Investigaciones Científicas y Técnicas, Ciudad Autonoma de Buenos Aires C1425FQB and Avilés Félix, Luis and Alejandro, Gabriela and Centro Atómico Bariloche, Bariloche, Rio Negro 8400 and Sirena, Martín and Centro Atómico Bariloche, Bariloche, Rio Negro 8400 and Instituto Balseiro-CNEA & Univ. Nac. de Cuyo, Bariloche, Rio Negro 8400},
abstractNote = {We report on the interlayer exchange coupling across insulating barriers observed on Ni{sub 80}Fe{sub 20}/Ba{sub 0.05}Sr{sub 0.95}TiO{sub 3}/La{sub 0.66}Sr{sub 0.33}MnO{sub 3} (Py/BST{sub 0.05}/LSMO) trilayers. The coupling mechanism has been analyzed in terms of the barrier thickness, samples' substrate, and temperature. We examined the effect of MgO (MGO) and SrTiO{sub 3} (STO) (001) single-crystalline substrates on the magnetic coupling and also on the magnetic anisotropies of the samples in order to get a deeper understanding of the magnetism of the structures. We measured a weak coupling mediated by spin-dependent tunneling phenomena whose sign and strength depend on barrier thickness and substrate. An antiferromagnetic (AF) exchange prevails for most of the samples and smoothly increases with the barrier thicknesses as a consequence of the screening effects of the BST{sub 0.05}. The coupling monotonically increases with temperature in all the samples and this behavior is attributed to thermally assisted mechanisms. The magnetic anisotropy of both magnetic components has a cubic symmetry that in the case of permalloy is added to a small uniaxial component.},
doi = {10.1063/1.4960639},
journal = {Applied Physics Letters},
number = 6,
volume = 109,
place = {United States},
year = {Mon Aug 08 00:00:00 EDT 2016},
month = {Mon Aug 08 00:00:00 EDT 2016}
}
  • In the present work, (1-x)Ba{sub 0.95}Sr{sub 0.05}TiO{sub 3}-(x)CoFe{sub 1.8}Mn{sub 0.2}O{sub 4} composites are prepared by standard solid state reaction method. The X-ray diffraction measurement of the composites shows that both the phases coexist in the composite, individually. The morphology of the composites were examined by field emission scanning electron microscopy and reveals homogeneous microstructure with two types of grains, smaller grains of the Ba{sub 0.95}Sr{sub 0.05}TiO{sub 3} (BST) and bigger grains of the CoFe{sub 1.8}Mn{sub 0.2}O{sub 4} (CFM). The dielectric studies show that all the composites exhibit dispersion in the lower frequency region attributable to the interfacial polarization. In addition,more » at lower frequencies, the dielectric constant (ε´) is found to increase with increase in CFM content in the composites. The ferromagnetic properties of the composites improve with the increase in the CFM content.« less
  • In this investigation, (1-x)(Bi{sub 0.9}La{sub 0.1})(Ga{sub 0.05}Fe{sub 0.95})O{sub 3}-x(Pb{sub 0.9}Ba{sub 0.1})TiO{sub 3}(BLGF= -PBT) crystalline solutions have been fabricated by using the solid-state reaction method. A ferroelectric rhombohedral/tetragonal morphotropic phase boundary (MPB) of (1-x)BLGF-xPBT was observed for x=0.4. In the vicinity of MPB, 0.6BLGF-0.4PBT revealed the maximum dielectric constant K and piezoelectric d{sub 33} constant of 1168 and 186 pC/N, respectively. The substitution of 10 at. % Ba for Pb dramatically increased K and d{sub 33} of (1-x)BLGF-xPBT relative to (1-x)BLGF-xPT at the same x content. The Curie temperature T{sub c} of (1-x)BLGF-xPBT was determined to be above 386 deg. Cmore » through the compositions investigated. The phase diagram of (1-x)BLGF-xPBT revealed a V-shaped relationship between T{sub c} and x content. The planar coupling coefficient K{sub p} was measured to be 0.37 for 0.6BLGF-0.4PBT, which was stable with increasing the measurement temperature until 170 deg. C. It is demonstrated that BLGF-PBT is a competitive alternative piezoelectric material, with the superior piezoelectricity and lead-reduced composition.« less
  • Multiferroic xBa{sub 0.95}Sr{sub 0.05}TiO{sub 3}-(1-x)BiFe{sub 0.90}Gd{sub 0.10}O{sub 3} [xBST-(1-x)BFGO] (x = 0.00, 0.10 and 0.20) ceramics were prepared by the standard solid-state reaction technique. Crystal structure of the ceramics was determined by X-ray diffraction pattern. All the compositions exhibited rhombohedral crystal structure. The tolerance factor ‘t’ varied from 0.847 to 0.864. The AC conductivity spectrum followed the Jonscher’s power law. The Nyquist plots indicated that only grains have the contribution to the resistance in this material and the values of grain resistance (R{sub g}) increased with BST content. The real part of complex initial permeability decreased with the increase inmore » frequency and increased with increasing BST content. Magnetoelectric coefficient was determined for all compositions. The maximum value of magnetoelectric coefficient was found to be 1.467 mV.cm{sup −1}.Oe{sup −1} for x = 0.20.« less
  • This paper describes the particle size characterization of mechanically alloyed Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} prepared with the aid of a high-power ultrasonic destruction. Analytical-grade BaCO{sub 3}, TiO{sub 2} and SrCO{sub 3} with a purity greater than 99 wt.% were used as precursors for Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3}. The mechanically powders were respectively sintered at 1200 °C for 3 hours to form crystalline powders. This work is aimed at studying the effect of diameter ratio between reactor and transducer of a high power sonicator on the Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} andmore » Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} nanoparticles formation. The presence of a single phase of the two materials was confirmed by X-Ray Diffraction (XRD). The concentration of the particles in demineralized water was 3.0 g / 100 mL which become the object of 3 hours ultrasonic destruction subjected to the application of transducer in which the ratio between the diameter of the reactor and the transducer (D/d) was fixed at 1.4, 1.6 and 1.8 respectively. It was found that the mean particle size before the ultrasonic destruction was 538 nm for Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and 480 nm for Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3}. With D/d of 1.8, the mean particle size of the two materials was found to decrease drastically to 38 nm and 24 nm, respectively. These mean particle sizes were respectively comparable with that of the crystallite size of the particles derived using the Whole Powder Pattern Modelling (WPPM) from which the mean crystallite size of 22 nm for Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and 14 nm for Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} were obtained. It is then confirmed single nanocrystallite Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} particles were already achieved. We can conclude that the ultrasonic destruction to mechanically milled crystalline particles would be one of an effective way to produce nanoparticles.« less
  • This article demonstrates the colossal energy harvesting capability of a lead-free (Bi{sub 0.5}Na{sub 0.5}){sub 0.915}-(Bi{sub 0.5}K{sub 0.5}){sub 0.05}Ba{sub 0.02}Sr{sub 0.015}TiO{sub 3} ceramic using the Olsen cycle. The maximum harvestable energy density estimated for this system is found to be 1523 J/L (1523 kJ/m{sup 3}) where the results are presented for extreme ambient conditions of 20–160 °C and electric fields of 0.1–4 MV/m. This estimated energy density is 1.7 times higher than the maximum reported to date for the lanthanum-doped lead zirconate titanate (thin film) system. Moreover, this study introduces a generalized and effective solid state refrigeration cycle in contrast to the ferroelectric Ericsonmore » refrigeration cycle. The cycle is based on a temperature induced polarization change on application of an unipolar electric field to ferroelectric ceramics.« less