Substrate-modified ferrimagnetism in MnGa films

Feng, Wuwei; Thiet, Duong Van; Dũng, Đặng Đức; Shin, Yooleemi; Cho, Sunglae

doi:10.1063/1.3517083

Cited by 41 publications

(31 citation statements)

References 19 publications

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“…In contrast to the epitaxial sample, M(H) of the nanostructured film has a wide "s"-shaped major hysteresis (irreversibility) loop. The coercive field for the nanostructured film is exceptionally large,  o H C = 2.5 T. This is much larger than the coercive field for the epitaxial film,  o H C = 0.36 T, which is typical of other high-quality epitaxial films [11][12][13]15 and bulk samples 6 . The magnetism of nanostructured films is robust with respect temperature.…”

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confidence: 88%

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Large coercivity in nanostructured rare-earth-free MnxGa films

Nummy

Bennett

Cardinal

et al. 2011

Applied Physics Letters

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The magnetic hysteresis of Mn x Ga films exhibit remarkably large coercive fields as high as  o H C = 2.5 T when fabricated with nanoscale particles of a suitable size and orientation. This coercivity is an order of magnitude larger than in wellordered epitaxial film counterparts and bulk materials. The enhanced coercivity is attributed to the combination of large magnetocrystalline anisotropy and ~ 50 nm size nanoparticles. The large coercivity is also replicated in the electrical properties through the anomalous Hall effect. The magnitude of the coercivity approaches that found in rare-earth magnets, making them attractive for rareearth-free magnet applications.Rare-earth-based magnets provide the backbone of many products, from computers and mobile phones to electric cars and wind-powered generators. 1 But because of the high cost and limited availability of rare-earth and precious elements, which are expensive to mine and process, there is a growing interest in developing new magnetic materials without these elements. [2][3][4] This critical need has fostered innovative research aimed at the discovery of novel compounds and nanoscale composites that are free of these elements. One of the key properties of super strong magnets is their large magnetocrystalline anisotropy. With this in mind, it is advantageous to search for rare-earth-free ferromagnets that have large anisotropies, such as MnAl and Mn x Ga. However, in order to take advantage of the large anisotropy and make them suitable for applications they must be synthesized with an appropriate composition and structure at the nanoscale level. We find that when the Heusler compound Mn x Ga is synthesized with the proper nanostructuring, a remarkably high coercive field is produced. These results suggest that Mn x Ga is a good candidate for producing materials with enhanced coercive fields aimed at replacing some rare-earth-based magnets in use today.

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confidence: 88%

“…Despite the particle-like growth, all of the films had metallic conductivity with longitudinal resistivities in the range ρ = 200 to 300 ·cm, very similar to that measured in epitaxial films. 11,15 Figure 3 shows results of room temperature Hall effect measurements of a 20 nm thick nanostructured Mn x Ga film. In Fig.…”

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confidence: 99%

Large coercivity in nanostructured rare-earth-free MnxGa films

Nummy

Bennett

Cardinal

et al. 2011

Applied Physics Letters

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“…Moreover, it was reported that the substrate modifies the magnetic properties of L1 0 -Mn x Ga (1.2ox o1.5) films. Particularly, the Mn x Ga film is a hard ferrimagnet when grown on GaSb (111), becomes a soft ferrimagnet when grown on Al 2 O 3 (0001), and exhibits an absence of a net magnetic moment when stabilized on a GaSb (100) substrate [33]. These results may be helpful in modifying magnetic anisotropy in thin films for spintronic applications.…”

Section: Introductionmentioning

confidence: 94%

“…Previous experimental results have shown that the Mn-Ga alloys grown on substrate or in superlattices have affected the tetragonality of the crystal structures, which is attributed to the lattice strain, and this has influence on the magnetic properties and the magnetocrystalline anisotropy of the alloys [18,[30][31][32][33][34][35][36]. It was found that the crystalline orientation of the Ferromagnetic L1 0 -MnGa thin films, which epitaxially grown on GaN, sapphire, and MgO substrates, differ due to the influence of the substrate [32].…”

Section: Introductionmentioning

confidence: 99%

Strain control of magnetocrystalline anisotropy and energy product of MnGa alloys

Al-Aqtash

Sabirianov

2015

Journal of Magnetism and Magnetic Materials

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a b s t r a c tWe investigate the energy product of MnGa alloys as function of Mn concentration and applied elastic strain. Using the density functional theory (DFT) based method we calculated the magnetocrystalline anisotropy (MAE) and magnetization of Mn-Ga alloys as function of composition, e.g. Mn and Ga, and examined their variation under applied strain. Our calculations show that MAE is very large $ 22-27 M erg/cm 3 in all three considered compositions, e.g. MnGa, Mn 3 Ga and Mn 1.66 Ga. We show that MAE is very robust in MnGa system and remains large in wide range of concentrations and strains both compressive and tensile. We find that bi-axial tensile strain increases MAE in Mn 1.66 Ga alloys. Our study shows that the variation of MAE as function of Mn content is related to the change in electronic structure and, specifically, the Fermi level position with electron population variation. We estimated the theoretical limit of the energy product (BH) max of MnGa, Mn 3 Ga and Mn 1.66 Ga alloys as 23.65, 4.06 and 13.64 MGOe, respectively. We find that volume expansion of the MnGa alloys (by appropriate doping) should increase the magnetization and the energy product of these alloys.

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“…The reported coercivities of L1 0 -MnGa films and powders are in the range of 2.2-6.2 kOe, which is not sufficiently high to qualify as a candidate for rare-earth-free magnets. [6][7][8][9][10][11] The D0 22 -Mn 3 Ga intermetallic compound, known as the Al 3 Ti-type MnGa phase, also has a tetragonal structure (I4/mmm). 12 Three different Mn 3 Ga intermetallic compounds are known to exits: the tetragonal D0 22 -Mn 3 Ga intermetallic compound, hexagonal D0 19 -Mn 3 Ga intermetallic compound, and cubic L2 1 -Mn 3 Ga intermetallic compound.…”

Section: Introductionmentioning

confidence: 99%

High coercivity in Mn-Ga-Cu alloys

Saito

Nishio–Hamane

2016

AIP Advances

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Mn-Ga-Cu alloys were produced by melt-spinning and subsequent annealing. The coercivity of the Mn-Ga-Cu alloys was dependent on the Cu content and the annealing conditions. The coercivity of the Mn65Ga20Cu15 alloy annealed at 573 K for 10 h, iHc = 23.8 kOe, was comparable to that of rare-earth-based magnets. The hard magnetic phase of the Mn65Ga20Cu15 alloy was found to be fine D022-Mn3Ga grains, formed from the fcc phase during annealing.

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Substrate-modified ferrimagnetism in MnGa films

Cited by 41 publications

References 19 publications

Large coercivity in nanostructured rare-earth-free MnxGa films

Large coercivity in nanostructured rare-earth-free MnxGa films

Strain control of magnetocrystalline anisotropy and energy product of MnGa alloys

High coercivity in Mn-Ga-Cu alloys

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