TETRAGONAL HEUSLER-LIKE <font>Mn</font>–<font>Ga</font> ALLOYS BASED PERPENDICULAR MAGNETIC TUNNEL JUNCTIONS

Ma, Qingxia; Sugihara, Akio; Suzuki, Kazuya; Zhang, Xianmin; Miyazaki, T.; Mizukami, Shigemi

doi:10.1142/s2010324714400244

Cited by 25 publications

(12 citation statements)

References 105 publications

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“…5(b) . The variation of H c for the MnGa layer in the figure is larger than that observed in thick MnGa films 24 , which could be partially explained by a small reduction of the Curie temperature T c and/or two-dimensionality of the thin-layer, as a significant increase of H c is also observed for the top CoFeB layer with PMA in Fig. 5(a) .…”

Section: Resultsmentioning

confidence: 69%

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Perpendicular magnetic tunnel junction with a strained Mn-based nanolayer

Suzuki

Ranjbar

Okabayashi

et al. 2016

Sci Rep

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A magnetic tunnel junction with a perpendicular magnetic easy-axis (p-MTJ) is a key device for spintronic non-volatile magnetoresistive random access memory (MRAM). Co-Fe-B alloy-based p-MTJs are being developed, although they have a large magnetisation and medium perpendicular magnetic anisotropy (PMA), which make it difficult to apply them to a future dense MRAM. Here, we demonstrate a p-MTJ with an epitaxially strained MnGa nanolayer grown on a unique CoGa buffer material, which exhibits a large PMA of more than 5 Merg/cm3 and magnetisation below 500 emu/cm3; these properties are sufficient for application to advanced MRAM. Although the experimental tunnel magnetoresistance (TMR) ratio is still low, first principles calculations confirm that the strain-induced crystal lattice distortion modifies the band dispersion along the tetragonal c-axis into the fully spin-polarised state; thus, a huge TMR effect can be generated in this p-MTJ.

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Section: Resultsmentioning

confidence: 69%

“…This is crucial for devices driven by the STT effect. However, this has not yet been achieved, because growth of Mn-based alloy nanolayers on conventional buffer layers, such as Cr, has deteriorated their PMA 24 25 26 27 28 .…”

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confidence: 99%

Perpendicular magnetic tunnel junction with a strained Mn-based nanolayer

Suzuki

Ranjbar

Okabayashi

et al. 2016

Sci Rep

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“…Mn 3 Ga has been proposed as a compensated ferrimagnet having a high spin polarisation of 88%, hard magnetic properties, and a high Curie temperature T c (730 K) [3,4]. Epitaxial growth of Mn-Ga thin films with high PMA [5,2] and multilayer devices with high tunnelling magnetoresistance (TMR) [6,7,8,9] have been realised.…”

Section: Introductionmentioning

confidence: 99%

Magnetic dichroism study on Mn_1.8Co_1.2Ga thin film using a combination of x-ray absorption and photoemission spectroscopy

Ouardi¹,

Fecher²,

Kubota³

et al. 2015

J. Phys. D: Appl. Phys.

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Abstract.Using circularly polarised radiation and a combination of bulk-sensitive hard X-ray photoelectron spectroscopy and X-ray-absorption spectroscopy (XAS) we studied the electronic and magnetic structure of epitaxial Mn 1.8 Co 1.2 Ga thin films. Spin resolved Bloch spectral functions, density of states as well as charge and magnetisation densities were investigated by a first-principles analysis of full potential, fully relativistic Korringa-Kohn-Rostoker calculations of the electronic structure. The valence states were experimentally investigated by using linear dichroism in the angular distribution and comparing the results to spin-resolved densities of states. The linear dichroism in the valence band enabled a symmetry analysis of the contributing states. The spectra were in good agreement with the theoretical partial density of states. The element-specific, spin-resolved, unoccupied densities of states for Co and Mn were analysed by using XAS and X-ray magnetic circular dichroism (XMCD) at the L 3,2 edges. The spectra were influenced by strong correlation effects. XMCD was used to extract the site resolved magnetic moments. The experimental values of m Mn = 0.7 µ B and m Co = 1.05 µ B agree very well with the calculated magnetic moments. Magnetic circular dichroism in angle-resolved photoelectron spectroscopy at the Mn and Co 2p core level exhibited a pronounced magnetic dichroism and confirmed the localised character of the Mn d valence states.

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“…Ferrimagnetic Mn 3 Ga with D0 22 structure is the most famous example which emerged as a well-suited candidate for spintronic devices, having high magnetocrystalline anisotropy, low magnetization, and small damping factor [16][17][18][19]. Mn 3 Ga was already considered for perpendicular magnetic tunnel junctions [20], but did not yield the high tunneling magnetoresistance ratio (TMR) expected by theory. Similarly, thin films of the D0 22 Mn 3 Ge phase have also attracted attention in the past years [21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Tunable magnetic properties in tetragonal Mn-Fe-Ga Heusler films with perpendicular anisotropy for spintronics applications

Kalache

Selle

Schnelle

et al. 2018

Phys. Rev. Materials

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High perpendicular magnetic anisotropy is essential for the development of high-efficiency spintronics devices. In this paper, we investigate the structural and magnetic properties of Mn-Fe-Ga Heusler thin films with perpendicular magnetic anisotropy inherent to the tetragonal D0 22 structure. High quality films were heteroepitaxially grown on SrTiO 3 substrates by magnetron sputtering technique. The magnetic properties such as saturation magnetization and coercive field are easily tunable by the variation of the Mn/Fe ratio, while retaining out-of-plane magnetization over large composition range. The uniaxial anisotropy was improved in Mn 2.6−x Fe x Ga 1.4 through Fe substitution at a fixed Ga excess. Films with composition Mn 1.6 Fe 1 Ga 1.4 were found to be stable down to a thickness of 10 nm. Transmission electron microscopy investigations proved the high quality of the films as well as chemical homogeneity. The Hall effect exhibits an anomalous contribution that dominates over the normal part, leading to Hall angle as high as 3.4%. These findings suggest great potential for the integration of tetragonal Heusler materials into spintronic devices.

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TETRAGONAL HEUSLER-LIKE Mn–Ga ALLOYS BASED PERPENDICULAR MAGNETIC TUNNEL JUNCTIONS

Cited by 25 publications

References 105 publications

Perpendicular magnetic tunnel junction with a strained Mn-based nanolayer

Perpendicular magnetic tunnel junction with a strained Mn-based nanolayer

Magnetic dichroism study on Mn_1.8Co_1.2Ga thin film using a combination of x-ray absorption and photoemission spectroscopy

Tunable magnetic properties in tetragonal Mn-Fe-Ga Heusler films with perpendicular anisotropy for spintronics applications

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TETRAGONAL HEUSLER-LIKE Mn–Ga ALLOYS BASED PERPENDICULAR MAGNETIC TUNNEL JUNCTIONS

Cited by 25 publications

References 105 publications

Perpendicular magnetic tunnel junction with a strained Mn-based nanolayer

Perpendicular magnetic tunnel junction with a strained Mn-based nanolayer

Magnetic dichroism study on Mn1.8Co1.2Ga thin film using a combination of x-ray absorption and photoemission spectroscopy

Tunable magnetic properties in tetragonal Mn-Fe-Ga Heusler films with perpendicular anisotropy for spintronics applications

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Magnetic dichroism study on Mn_1.8Co_1.2Ga thin film using a combination of x-ray absorption and photoemission spectroscopy