skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Magnetic Transitions in Lattice-matched, Ordered FePt 3 Based Antiferromagnetic/ferromagnetic Films

Abstract

Measurements of lattice-matched antiferromagnetic/ferromagnetic films which are ideal layered systems to study exchange bias are reported. Epitaxial films of FePt{sub 3} have two kinds of antiferromagnetic ordering. The spin ordering phase with wave vector Q{sub 1} = (1/2 1/2 0) has a Neel temperature T{sub N} = 160 K and that with wave vector Q{sub 2} = (1/2 0 0) has T{sub N} = 100 K. Neutron diffraction confirmed the presence of Q{sub 2} = (1/2 0 0) antiferromagnetic ordering in 200 nm Fe{sub 25}Pt{sub 75} grown on MgO(100). The loop shift and coercivity of a trilayer film of CoPt{sub 3}/FePt{sub 3}/CoPt{sub 3} decrease with increasing temperature, consistent with the observed Neel temperature of FePt{sub 3}. The x-ray diffraction rocking curve widths of films grown on MgO(100) and Al{sub 2}O{sub 3}(11{bar 2}0) are compared and related to the loop shifts that are observed in the films with lattice-matched antiferromagnetic/ferromagnetic interfaces.

Authors:
 [1];  [2];  [2];  [2];  [1]
  1. University of Alabama, Tuscaloosa
  2. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); High Flux Isotope Reactor
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1003572
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 99; Journal Issue: 8
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; NEEL TEMPERATURE; NEUTRON DIFFRACTION; SPIN; VECTORS; X-RAY DIFFRACTION

Citation Formats

Mani, P., Vemuru, Krishnamurthy V, Robertson, Lee, Klose, Frank Richard, and Mankey, G. J.. Magnetic Transitions in Lattice-matched, Ordered FePt3 Based Antiferromagnetic/ferromagnetic Films. United States: N. p., 2006. Web. doi:10.1063/1.2177347.
Mani, P., Vemuru, Krishnamurthy V, Robertson, Lee, Klose, Frank Richard, & Mankey, G. J.. Magnetic Transitions in Lattice-matched, Ordered FePt3 Based Antiferromagnetic/ferromagnetic Films. United States. doi:10.1063/1.2177347.
Mani, P., Vemuru, Krishnamurthy V, Robertson, Lee, Klose, Frank Richard, and Mankey, G. J.. Sun . "Magnetic Transitions in Lattice-matched, Ordered FePt3 Based Antiferromagnetic/ferromagnetic Films". United States. doi:10.1063/1.2177347.
@article{osti_1003572,
title = {Magnetic Transitions in Lattice-matched, Ordered FePt3 Based Antiferromagnetic/ferromagnetic Films},
author = {Mani, P. and Vemuru, Krishnamurthy V and Robertson, Lee and Klose, Frank Richard and Mankey, G. J.},
abstractNote = {Measurements of lattice-matched antiferromagnetic/ferromagnetic films which are ideal layered systems to study exchange bias are reported. Epitaxial films of FePt{sub 3} have two kinds of antiferromagnetic ordering. The spin ordering phase with wave vector Q{sub 1} = (1/2 1/2 0) has a Neel temperature T{sub N} = 160 K and that with wave vector Q{sub 2} = (1/2 0 0) has T{sub N} = 100 K. Neutron diffraction confirmed the presence of Q{sub 2} = (1/2 0 0) antiferromagnetic ordering in 200 nm Fe{sub 25}Pt{sub 75} grown on MgO(100). The loop shift and coercivity of a trilayer film of CoPt{sub 3}/FePt{sub 3}/CoPt{sub 3} decrease with increasing temperature, consistent with the observed Neel temperature of FePt{sub 3}. The x-ray diffraction rocking curve widths of films grown on MgO(100) and Al{sub 2}O{sub 3}(11{bar 2}0) are compared and related to the loop shifts that are observed in the films with lattice-matched antiferromagnetic/ferromagnetic interfaces.},
doi = {10.1063/1.2177347},
journal = {Journal of Applied Physics},
number = 8,
volume = 99,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • The Fe{sub x}Pt{sub 100−x} nanoparticles (NPs) with different nominal atomic rations (30≤x≤80) were synthesized at 700 °C by the sol–gel method. The structure, morphology and magnetic properties of the samples were investigated. When the Fe content in the Fe–Pt alloy NPs was 30 at%, FePt{sub 3} NPs were successfully synthesized. With the increase in Fe content up to 50 at%, it was found that the superlattice reflections (0 0 1) and (1 1 0) appeared, which indicated the formation of the L1{sub 0}-FePt phase. Meanwhile, the FePt{sub 3} fraction was reduced. When the Fe content increased to 60 at%, single-phasemore » L1{sub 0}-FePt NPs were synthesized. The coercivity (Hc), saturation magnetization (Ms) and chemical order parameter S for Fe{sub 60}Pt{sub 40} NPs were as high as 10,200 Oe, 17.567 emu/g and 0.928, respectively. With the further increase of the Fe content to 80 at%, only Fe{sub 3}Pt phase existed and the Hc of the Fe{sub 3}Pt NPs decreased drastically to 360 Oe. - Graphical abstract: Fe{sub 3}Pt, FePt and FePt{sub 3} nanoparticles was obtained by sol–gel method. The effect of iron and platinum content on structural and magnetic properties of the FePt nanoparticles was investigated. Display Omitted - Highlights: • L1{sub 2}-FePt{sub 3}, L1{sub 0}-FePt and L1{sub 2}-Fe{sub 3}Pt NPs were synthesized by sol–gel method. • The chemical order parameter S affects the magnetic properties of the Fe–Pt alloy. • Structural and magnetic properties of the Fe–Pt alloy NPs were studied. • The synthetic route in this study will open up the possibilities of practical use.« less
  • The magnetism of antiferromagnetic Fe{sub x}Pt{sub 1-x} thin films (x=0.27 and 0.30) epitaxially grown onto MgO (110) and a-axis sapphire ({alpha}-Al{sub 2}O{sub 3}) substrates has been studied by elastic neutron and x-ray scattering. Bulk chemically ordered FePt{sub 3} exhibits an antiferromagnetic spin structure with a wave vector Q{sub 1}=2{pi}/a(1/2 1/2 0) below T{sub N1}{approx}160K. For slightly Fe-rich alloys (x{approx}>0.26) a spin-reorientation transition to a second antiferromagnetic phase with a wave vector Q{sub 2}=2{pi}/a(1/2 00) occurs below T{sub N2}{approx}100K at the expense of Q{sub 1}. For increased Fe content (x{approx}0.30) the Q{sub 1} phase is strongly suppressed with a dominant Q{submore » 2} phase. For (111)-oriented films grown on a-axis sapphire the spin structure is the same as that found in the bulk. The x=0.27 film exhibits transitions at T{sub N1} and T{sub N2}. The film with x=0.30 exhibits an almost completely suppressed Q{sub 1} phase and a dominant Q{sub 2} phase with an enhanced ordering temperature of T{sub N2}{approx}140K. In contrast FePt{sub 3} (110) films grown onto MgO (110) exhibit only the Q{sub 1} phase for both compositions x=0.27 and x=0.30 with the onset of the Q{sub 2} phase suppressed. The distinct behavior of the films grown onto MgO from those grown onto a-axis sapphire and bulk FePt{sub 3} may be explained by higher strain and defect densities incorporated in the films grown onto MgO.« less
  • Sr{sub 2}Cu{sub 3}O{sub 4}Cl{sub 2} is a variant of the lamellar copper oxides, containing an extra Cu{sup 2+} ion in the center of every second plaquette of the square CuO{sub 2} lattice. The two types of Cu form interpenetrating Heisenberg antiferromagnets, which order at 380 and 40 K. Magnetization measurements yield a small spontaneous ferromagnetic moment below 380 K and two spin rotation transitions. The results are explained in detail by a pseudodipolar coupling between the two Cu lattices. A quantitative analysis of the data yields several previously unknown microscopic coupling constants, relevant to other lamellar, chain, and ladder coppermore » oxides. {copyright} {ital 1997} {ital The American Physical Society}« less
  • L1{sub 0}–FePt(001) single-crystal films were grown epitaxially on SrTiO{sub 3}(001), MgAl{sub 2}O{sub 4}(001), and MgO(001) substrates. Their uniaxial magnetic anisotropy K{sub u} and the order structure were examined for the film thickness t range of 2–14 nm. All series of films show large K{sub u} of 4 × 10{sup 7} erg/cm{sup 3} in the thickness range higher than 10 nm, with order parameter S of 0.8 and saturation magnetization M{sub s} of 1120 emu/cm{sup 3}. K{sub u} decreased gradually as t decreased. The K{sub u} reduction was considerable when t decreased from 4 nm to 2 nm. No marked difference in the thickness dependence of K{sub u} wasmore » found in any series of films, although the lattice mismatch between FePt and the substrates was markedly different. K{sub u} reduction showed good agreement with the reduction of S for the films on MgAl{sub 2}O{sub 4} and MgO. The K{sub u} ∼ S{sup 2} plot showed an almost linear relation, which is in good agreement with theoretical predictions. Transmission electron microscopy images for a FePt film on MgO substrate revealed that the lattice mismatch between FePt(001) and MgO(001) was relaxed in the initial 1 or 2 layers of FePt(001) lattices, which is likely to be true also for two other series of films.« less