Microstructure and electric property of MgO/Fe/MgO tri-layer films forming a nano-granular system

Arita, Masashi; Wakasugi, Kosuke; Ohta, Katsumi; Hamada, K.; Takahashi, Yasuo; Choi, Jihun

doi:10.1016/j.mee.2008.09.025

Cited by 10 publications

(13 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…14 Despite extensive research on planar Fe/ MgO/Fe MTJs, little attention has been paid to Fe/MgO granular cermets. 15,16 In this paper we present our results on the magnetotransport properties of Fe/MgO DMIMs prepared by pulsed laser deposition ͑PLD͒.Polycrystalline ͓Fe͑t͒ / MgO͑3 nm͔͒ N multilayers with 0.4 nmՅ t Յ 1.5 nm were deposited by PLD on glass substrates. The preparation procedure was reported in detail elsewhere.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Tunneling magnetoresistance in Fe/MgO granular multilayers

García-García

Vovk

Pardo

et al. 2010

Journal of Applied Physics

View full text Add to dashboard Cite

We have investigated the transport and magnetotransport properties in Fe/MgO multilayers around the Fe percolation threshold as a function of the temperature and the nominal thickness of iron layer ͑t͒. Electrical resistivity measurements allowed us to disclose the charge transport mechanisms involved, which are closely related to the degree of discontinuity in the Fe layers. The samples with Fe thickness below percolation threshold ͑t ϳ 0.8 nm͒ exhibit isotropic magnetoresistance ͑MR͒, which can be understood considering spin-polarized electron tunneling between nanometer-sized, superparamagnetic Fe grains. The MR ratio increases with decreasing temperature from ϳ3% at room temperature to ϳ10% at 30 K. The temperature dependence of MR can be explained satisfactorily in terms of a modified Mitani's model. © 2010 American Institute of Physics. ͓doi:10.1063/1.3298504͔A new generation of devices combining the advantages of semiconductor electronics with spin-dependent transport is emerging as a consequence of the strong potential for magnetoelectronic applications, such as storage media, sensors, and potentiometers. 1 The interest in the development of these spintronic devices inspired the search for new materials in the nanometric length scale, where the magnetic and transport properties differ substantially from those of the bulk. Among them we can mention granular cermets-in which nanometer-sized magnetic metallic particles are embedded in an insulating matrix. [2][3][4][5] Discontinuous metal-insulator multilayers ͑DMIMs͒ are a special kind of granular cermets where the metallic particles are located not randomly but in layers, and this arrangement causes the enhancement of the low-field dependence and relatively high magnetoresistance ͑MR͒ ratios at room temperature. 6 DMIMs are easier to prepare than planar, epitaxial magnetic tunnel junctions ͑MTJs͒ showing huge MR values, 7,8 but strongly reduced by structural defects at interfaces. 9,10 The physical principle that underlies the MR in both cases is a spin-dependent electric charge transfer between two magnetized electrodes or grains via tunneling effect. 11,12 This effect is called tunneling MR ͑TMR͒, and the tunneling probability depends on the relative orientation of magnetization of the electrodes or grains. 13 Experimentally TMR ratios up to 180% in fully epitaxial Fe͑001͒/ MgO͑001͒/Fe͑001͒ junction were found at room temperature, 7 and first-principles calculations predict even higher values. 14 Despite extensive research on planar Fe/ MgO/Fe MTJs, little attention has been paid to Fe/MgO granular cermets. 15,16 In this paper we present our results on the magnetotransport properties of Fe/MgO DMIMs prepared by pulsed laser deposition ͑PLD͒.Polycrystalline ͓Fe͑t͒ / MgO͑3 nm͔͒ N multilayers with 0.4 nmՅ t Յ 1.5 nm were deposited by PLD on glass substrates. The preparation procedure was reported in detail elsewhere. 16 Electrical resistance and MR measurements were carried out using the four-point method in the temperature range 30-295 K and in-plane app...

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%

Tunneling magnetoresistance in Fe/MgO granular multilayers

García-García

Vovk

Pardo

et al. 2010

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…The outermost multilayers presented resistance values beyond our experimental limit. All the samples exhibit values for resistivity much larger than those reported for bulk Fe (ρ Fe = 9.7 µ ·cm) and in Fe ultrathin continuous films (10 2 -10 3 µ ·cm) [14,16,31], where 2-dimensional confinement effects lead to a decrease in carrier mean free path [32]. This result confirms that the samples are discontinuous, as has been demonstrated previously by M(H ) measurements, and transport behavior of the samples is governed by tunneling effect between adjacent Fe grains.…”

Section: Resultsmentioning

confidence: 73%

“…However, conditions for continuous coverage do not fulfil and a granular structure is formed. For each particular metal/insulator system, the nominal thickness together with deposition and post-deposition conditions allow controlling the shape and size of the metal granules [11,12,[15][16][17], which in turn determine the magnetic, transport and magnetotransport behavior of these multilayers. In fact, dramatic changes in their properties take place around the percolation thickness of the metal phase.…”

Section: Introductionmentioning

confidence: 99%

Combinatorial pulsed laser deposition of Fe/MgO granular multilayers

et al. 2012

View full text Add to dashboard Cite

Combinatorial pulsed laser deposition (PLD) makes use of the angular spread of laser-ablated material to prepare thin films with lateral compositional gradient. In this paper we have used combinatorial PLD to grow discontinuous Fe/MgO multilayers by alternate ablation from two separate Fe and MgO targets. Films of composition [Fe(t Fe )/MgO(t MgO )] 15 were deposited on glass substrates. The thickness of Fe and MgO were varied in the vicinity of critical values determined in previous studies to maximize A. García-García ( ) · P.A. Algarabel A. Vovk Institute of Magnetism NAS of Ukraine, 36-b Vernnadsky blvd., 03142 Kiev, Ukraine the tunneling magnetoresistance (TMR) in the current-inplane configuration. Optimized multilayers show a substantial improvement of both TMR and field sensitivity at room temperature.

show abstract

“…[5][6][7][8] More recently the Fe-MgO system has been used as a canvas to explore relationships between microstructure and magnetism for potential device applications. [9][10][11][12] It is known that Fe island coverage and interconnectivity can introduce configurational magnetic anisotropy that dominates over magnetocrystalline anisotropy. 13 This results in a rounding of hysteresis loops, which depends on island size and distribution, interfacial strain, and intermixing at the Fe and MgO interface.…”

mentioning

confidence: 99%

A study of the effect of iron island morphology and interface oxidation on the magnetic hysteresis of Fe-MgO (001) thin film composites

Spurgeon

Sloppy

Tao

et al. 2012

Journal of Applied Physics

View full text Add to dashboard Cite

Fe-MgO tunnel junctions have received much attention for their use in hard drive read heads and other spintronic applications. The system is particularly interesting because of its magnetoresistive behavior and the abundance and low cost of its constituent elements. However, many questions remain about how the structure and chemistry of the Fe-MgO interface mediates magnetic behavior. In this study, we report on transmission electron microscopy, electron energy loss spectroscopy, and magnetic characterization of Fe-MgO composite films with various morphologies. We explore relationships between film morphology, intermixing, and the resulting effects on magnetic structure. We find the presence of oxidation at the Fe-MgO interface, with a detrimental impact on the saturation magnetization of the composite. We also observe changes in coercivity and magnetocrystalline anisotropy with film morphology and thickness. These results will inform the design of MgO-based tunnel junctions and improve our understanding of how processing conditions, resulting in morphological and chemical changes such as oxidation, affect magnetization.

show abstract

Microstructure and electric property of MgO/Fe/MgO tri-layer films forming a nano-granular system

Cited by 10 publications

References 15 publications

Tunneling magnetoresistance in Fe/MgO granular multilayers

Tunneling magnetoresistance in Fe/MgO granular multilayers

Combinatorial pulsed laser deposition of Fe/MgO granular multilayers

A study of the effect of iron island morphology and interface oxidation on the magnetic hysteresis of Fe-MgO (001) thin film composites

Contact Info

Product

Resources

About