Magnetoresistance at grain boundaries artificially introduced into magnetite films

Ziese, M.; Höhne, R.; Hong, Nguyen Hoa; Dienelt, J.; Zimmer, Klaus; Esquinazi, P.

doi:10.1016/s0304-8853(01)01338-5

Cited by 9 publications

(5 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In our case, due to the preferential alignment of step edges along the direction perpendicular to the miscut, APBs are formed due to the presence of atomic height steps ͑0.21 nm͒ on MgO substrate ͑as described in detail in the preceding discussion͒. The terrace width ͑24.05 and 5.96 nm for 0.5°and 2°miscut, respectively͒ is quite small in comparison to the width of step edge array used by Ziese et al 29,30 The MR behavior of epitaxial magnetite thin films containing APBs has been analyzed by Eerenstein et al 25 and Zeise and Blythe 26 within one-dimensional models. Concerning the MR of the Fe 3 O 4 films on vicinal substrates, we noticed that contrary to the prediction of the models, the field dependence of MR deviates from a linear behavior below a certain temperature ͑130 K͒.…”

Section: Resultsmentioning

confidence: 65%

“…[25][26][27][28][29][30] Previous efforts by Ziese et al 29,30 to enhance the MR of epitaxial Fe 3 O 4 films grown on patterned MgO and MgAl 2 O 4 substrates having step edge array ͑80-120 nm step height and 10-20 m wide stripes͒ have not yielded substantial MR increase. They found that the anisotropy in MR with reference to the step-edge direction was not large ͑1.8% at 3 T,80 K͒ for the case of films grown on patterned MgO substrates, whereas they obtained relatively larger MR anisotropy for films grown on patterned MgAl 2 O 4 ͑5% at 3 T , 105 K͒.…”

Section: Resultsmentioning

confidence: 99%

“…29,30 The authors observed an enhancement in the MR that was not high in the low fields and was due to the spin-dependent electron transport across the magnetic clusters formed at the step edges. The studies [28][29][30] were not concerned with the APBs and indeed in the case of Fe 3 O 4 / MgAl 2 O 4 the APBs are not formed as the film and substrate have the same kind of symmetry.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Magnetoresistance enhancement in epitaxial magnetite films grown on vicinal substrates

2005

View full text Add to dashboard Cite

The magnetoresistance ͑MR͒ behavior of epitaxial magnetite Fe 3 O 4 grown on low-vicinal ͑small miscut͒ and high-vicinal ͑large miscut͒ MgO substrates is compared. Magnetization measurements on Fe 3 O 4 films on high-vicinal substrates showed reduced magnetic moment as compared with the films grown on low-vicinal MgO, which correlates well with the expected reduction in magnetic moment due to step edge induced additional antiphase boundaries ͑APBs͒ with out-of-plane shift vectors. The MR is significantly higher ͑12.3% at 2 T͒ for a 45 nm Fe 3 O 4 film on high-vicinal substrate than that observed ͑7.2% at 2 T͒ for a film on low-vicinal substrate. A strong anisotropy in the MR is observed in correlation with the direction of atomic step edges. In addition to the increase in MR, the field dependency of the MR is also modified. The observed modification in the magnetotransport behavior of epitaxial Fe 3 O 4 films is attributed to an enhanced spin scattering arising due to the presence of atomic height steps that lead to the formation of a greater density of antiferromagnetically coupled APBs.

show abstract

Section: Resultsmentioning

confidence: 65%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Magnetoresistance enhancement in epitaxial magnetite films grown on vicinal substrates

2005

View full text Add to dashboard Cite

show abstract

“…The observed value of MR is higher than any of the previously reported MR values for epitaxial magnetite films. 13,14,16 Another noticeable feature is that there is a significant enhancement in the low field MR. The MR shows a steep rise up to a field of 0.7 T and for higher magnetic fields ͑Ͼ0.7 T͒͒ there is a crossover to shallower field dependence.…”

Section: Resultsmentioning

confidence: 99%

Study of magnetoresistance of epitaxial magnetite films grown on vicinal MgO (100) substrate

Sofin

Arora

Shvets

2005

Journal of Applied Physics

View full text Add to dashboard Cite

The magnetoresistance ͑MR͒ studies of magnetite thin films deposited on vicinal MgO substrates show an enhanced MR along the miscut direction as compared to the direction perpendicular to it. The MR anisotropy increases with the decrease in temperature and peaks at the Verwey transition. The increase in magnetoresistance and anisotropy behavior is attributed to the formation of a greater number of out-of-plane shifted antiphase boundaries due to the step edges on vicinal MgO substrates. These local electronic and spin structure modifications at the APBs introduce additional spin scattering and are responsible for the increase in MR along the miscut. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1850361͔ INTRODUCTIONRecently, there has been considerable interest in the growth of magnetic thin films on vicinal surfaces owing to the intriguing physics involved and technological potential. [1][2][3][4] The studies on vicinal surfaces have been carried out mainly to understand the effect of lateral modulation of the electronic structure induced by step edges on the magnetic anisotropies. 3,4 In our previous publication we haveshown that the growth of Fe on stepped Mo ͑110͒ substrates leads to the formation of self-assembled nanowedges of size 20-40 nm and a switching of the magnetic easy axis from along the step edges to direction perpendicular to them. 3There are few reports on the study of magnetoresistance properties of thin films grown on vicinal surfaces. EXPERIMENTThe Fe 3 O 4 thin films were grown on ͑100͒ oriented MgO single crystal substrates using an oxygen plasma assisted molecular beam epitaxy ͑MBE͒ system ͑DCA MBE M600, Finland͒ with a base pressure 5 ϫ 10 −10 Torr. Details of the film growth procedure are given elsewhere. 15 In situ reflection high energy electron diffraction ͑RHEED͒ was used to confirm epitaxial growth and also the growth mode. From the RHEED intensity oscillations it was found that the films grew in a layer-by-layer mode ͑at a rate of 0.3 Å / s. In the present study we report results obtained on two representative samples named, sample A and sample B, in which the MgO ͑100͒ substrates have nominal miscut of 0.5°͑±0.05°͒ and 2°͑±0.05°͒ along ͗011͘ directions. Structural characterization of the samples was performed using a high-resolution x-ray diffractometer ͑HRXRD, Bede-D1, UK͒. Miscut of the samples was determined from the variation in Bragg angle for the symmetric diffraction for different azimuth.Electrical resistivity and magnetoresistance ͑MR͒ measurements were carried out in the standard dc four probe collinear configuration. A variable field ͑up to 2 T͒ permanent magnet ͑Model: MM 2000 26.5-001, Multimag Magnetic Solutions Ltd., Ireland͒ was used to apply magnetic fields in the desired orientation. The MR is defined as;where R͑H͒ and R͑0͒ are the resistance of the sample with and without field, respectively. To determine the magnetoresistance anisotropy, the measurements were carried out by passing current in two directions, which are orthogonal to each other, i.e., a...

show abstract

“…Below the Verwey transition, which is a charge ordering transition, the conductivity is strongly reduced and is due to nearest neighbour or variable range hopping [16]. There have been several attempts to search for grain-boundary magnetoresistance in magnetite samples [17][18][19][20][21][22][23][24][25][26][27][28], but the effects observed so far have been rather small. Most of the researchers believe that the transport mechanism involved is spin-polarized tunnelling.…”

Section: Introductionmentioning

confidence: 99%

Magnetic and magnetotransport properties of magnetite films with step edges

Ziese¹,

Höhne²,

Semmelhack³

et al. 2004

Journal of Magnetism and Magnetic Materials

Self Cite

View full text Add to dashboard Cite

Magnetoresistance at grain boundaries artificially introduced into magnetite films

Cited by 9 publications

References 12 publications

Magnetoresistance enhancement in epitaxial magnetite films grown on vicinal substrates

Magnetoresistance enhancement in epitaxial magnetite films grown on vicinal substrates

Study of magnetoresistance of epitaxial magnetite films grown on vicinal MgO (100) substrate

Magnetic and magnetotransport properties of magnetite films with step edges

Contact Info

Product

Resources

About