Anomalous resistivity upturn in epitaxial L21-Co2MnAl films

Zhu, Lihua; Zhao, Jianhua

doi:10.1038/srep42931

Cited by 33 publications

(15 citation statements)

References 30 publications

(73 reference statements)

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“…High-spin polarized Heusler ferromagnetisms seem to be ideal for applications in giant magneto-resistance (GMR) and tunneling magneto-resistance in magnetic tunneling junctions (MTJs). [8] Among these, Co 2 MnAl films may be introduced as ideal candidates for high-sensitive Hall sensors due to the unusual inherent Hall conductance [9][10][11]. So far, reports have been presented on the study of layered structure samples of Co 2 YZ (Y = Mn, Cr, Fe, Z = Al, Si, Ga).…”

Section: Introductionmentioning

confidence: 99%

The surface effect on the thermodynamic stability, half-metallic and optical properties of Co2MnGa(001) films: a DFT study

et al. 2019

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In this study, the half-metallic properties, thermodynamic stability and optical parameters of the full-Heusler Co 2 MnGa compound and its four different terminations of Co-Co, Co-Mn, Mn-Ga and Co-Ga from the surface of Co 2 MnGa (001) have been calculated based on the density functional theory (DFT). The results confirm the ferromagnetic half-metallic behavior with a magnetic moment of 4.08 B and a gap of 0.32 eV at the Fermi level of Co 2 MnGa bulk phase having a Cu 2 MnAl-type structure. The density of states curves showed that all possible terminations from the Co 2 MnGa (001) surface eliminate the half-metallic behavior except the termination of Mn-Ga case. Moreover, the results indicate that the termination of Mn-Ga with the lowest surface energy is the most stable termination for the application in spintronics. The optical coefficients such as real and imaginary dielectric function, refraction, extinction, energy loss function, optical conductivity and reflections of the bulk and Mn-Ga termination have been calculated and compared.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Section: Introductionmentioning

confidence: 99%

The surface effect on the thermodynamic stability, half-metallic and optical properties of Co2MnGa(001) films: a DFT study

et al. 2019

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“…Magnetic hysteresis loops of a 50 nm Co 2 MnGa film are measured with the external magnetic field along both the in-plane and out-of-plane directions at 300 K by the SQUID magnetometer, as shown in Figure 6.2(a). These show the easy axis is along the Co 2 MnGa [110] direction, the same as for other Heusler alloy thin films, like Co 2 MnAl and Co 2 MnSi [166,167], and the coercive field µ 0 H c and saturation magnetization M s are 3 mT, 6 × 10 5 A/m, respectively. Note that the crystalline direction used in this chapter refers to the Co 2 MnGa lattice, unless indicated otherwise.…”

Section: Magnetotransport Propertiessupporting

confidence: 68%

Skyrmion generation and perpendicular magnetic anisotropy modification in Heusler alloy ultrathin films

Zhang¹

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This thesis explores the magnetic properties of Heusler alloy thin films for spintronics applications. The skyrmion generation under different externalstimulation was focused in MgO/Mn2CoAl/Pd ultrathin films and the anomalous Hall effect of Co2MnGa thin films. The perpendicularly magnetized MgO/Mn2CoAl/Pd ultrathin films were firstly optimised by changing the thickness of Pd layer so that the effective magnetic anisotropy can be tuned and various magnetic textures can be obtained for different purposes. Based on the understanding of Pd dependence of magnetic properties, The skyrmion generation by applying an in-plane magnetic field was investigated to fine tune the effective magnetic anisotropy. Further the fractal analysis was used to describe the evolution of the magnetic states and categorise the formation of skyrmions. Then skyrmion generation by ionic liquid gating has been investigated in this trilayer. Both non-volatile and volatile skyrmions can be generated by applying a range of voltage sequences. The potential mechanisms, magneto-ionic and electrostatic charge effects, have been discussed as well. Finally, the thickness dependence of Co2MnGa thin films was studied. This material can be used as a spin-orbit generator for manipulating skyrmions. A large anomalous Hall angle (AHA) was demonstrated in Co2MnGa thin films (20 - 50 nm) showing a AHA ~11.4% at low temperature and ~9.7% at room temperature, which can be ascribed to the nontrivial topology of the band structure with large intrinsic Berry curvature. However, the anomalous Hall angle decreases significantly with thicknesses below 20 nm, which band structure calculations confirm is due to the reduction of the majority spin contribution to the Berry curvature.

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“…The rotation of the magnetic moment induces different local fields, which results in the spin-dependent scattering. 30 This interaction between current and the direction of the magnetic moment is similar to the effect of anisotropic magnetoresistance, which gives rise to the peak until the moment saturated around 10 000 Oe (ρ xx ⊥ > ρ xx || ). The system shows negative magnetoresistance even when all the magnetic moments have already been aligned in the hard axis which is typical ferromagnet behavior.…”

Section: Resultsmentioning

confidence: 85%

Heteroepitaxy of Co-Based Heusler Compound/Muscovite for Flexible Spintronics

Chen

Yen²,

Lai³

et al. 2019

ACS Appl. Mater. Interfaces

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Materials with high spin-polarization play an important role in the development of spintronics. Co-based Heusler compounds are a promising candidate for practical applications because of their high Curie temperature and tunable half-metallicity. However, it is a challenge to integrate Heusler compounds into thin film heterostructures because of the lack of control on crystallinity and chemical disorder, critical factors of novel behaviors. Here, muscovite is introduced as a growth substrate to fabricate epitaxial Co2MnGa films with mechanical flexibility. The feature of heteroepitaxy is evidenced by the results of X-ray diffraction and transmission electron microscopy. Moreover, high chemical ordering with superior properties is delivered according to the observation of large Hall conductivity (680 Ω–1 cm–1) and highly saturated magnetic moment (∼3.93 μB/f.u.), matching well with bulk crystals. Furthermore, the excellence of magnetic and electrical properties is retained under the various mechanical bending conditions. Such a result suggests that the development of Co2MnGa/muscovite heteroepitaxy provides not only a pathway to the thin film heterostructure based on high-quality Heusler compounds but also a new aspect of spintronic applications on flexible substrates.

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Anomalous resistivity upturn in epitaxial L21-Co2MnAl films

Cited by 33 publications

References 30 publications

The surface effect on the thermodynamic stability, half-metallic and optical properties of Co2MnGa(001) films: a DFT study

The surface effect on the thermodynamic stability, half-metallic and optical properties of Co2MnGa(001) films: a DFT study

Skyrmion generation and perpendicular magnetic anisotropy modification in Heusler alloy ultrathin films

Heteroepitaxy of Co-Based Heusler Compound/Muscovite for Flexible Spintronics

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