Structural ordering driven anisotropic magnetoresistance, anomalous Hall resistance and its topological overtones in full-Heusler Co2MnSi thin films

Abstract

We report the evolution of crystallographic structure, magnetic ordering and electronic transport in thin films of full-Heusler alloy Co${}_2$MnSi deposited on (001) MgO with annealing temperatures ($T_A$). By increasing the $T_A$ from 300${}^{\circ }$C to 600${}^{\circ }$C, the film goes from a disordered nanocrystalline phase to $B2$ ordered and finally to the $L{2}_1$ ordered alloy. The saturation magnetic moment improves with structural ordering and approaches the Slater-Pauling value of $\approx 5.0{\mu }_B$ per formula unit for $T_A$ = 600${}^{\circ }$C. At this stage the films are soft magnets with coercive and saturation fields as low as $\approx$ 7 mT and 350 mT, respectively. Remarkable effects of improved structural order are also seen in longitudinal resistivity (${\rho }_{xx}$) and residual resistivity ratio. A model based upon electronic transparency of grain boundaries illucidates the transition from a state of negative $d\rho /dT$ to positive $d\rho /dT$ with improved structural order. The Hall resistivity (${\rho }_{xy}$) derives contribution from the normal scattering of charge carriers in external magnetic field, the anomalous effect originating from built-in magnetization and a small but distinct topological Hall effect in the disordered phase. The carrier concentration ($n$) and mobility ($\mu$) have been extracted from the high field ${\rho }_{xy}$ data. The highly ordered films are characterized by $n$ and $\mu$ of 1.19$\times$ 10${}^{29}$ m${}^{-3}$ and 0.4 cm${}^2{V}^{-1}{s}^{-1}$ at room temperature. The dependence of ${\rho }_{xy}$ on ${\rho }_{xx}$ indicates the dominance of skew scattering in our films, which shows a monotonic drop on raising the $T_A$. The topological Hall effect is analyzed for the films annealed at 300${}^{\circ }$C. ......

arXiv comment10 pages, 9 figures, 1 table

References in corpus (17)

• Anomalous Hall effect
• Slater-Pauling Behavior of the Half-Ferromagnetic Full-Heusler Alloys
• Inverse magnetocaloric effect in ferromagnetic Ni-Mn-Sn alloys
• Topological Hall effect in the A-phase of MnSi
• Tunable Multifunctional Topological Insulators in Ternary Heusler Compounds
• A new platform for topological quantum phenomena : Topological Insulator states in thermoelectric Heusler-related ternary compounds
• Unusual Hall Effect Anomaly in MnSi Under Pressure
• Skyrmions and Anomalous Hall Effect in a Dzyloshinskii-Moriya Spiral Magnet
• Correlation in the transition metal based Heusler compounds Co${}_2$MnSi and Co${}_2$FeSi
• Anisotropic Magnetoresistance Effects in Fe, Co, Ni, Fe_4N, and Half-Metallic Ferromagnet: A Systematic Analysis
• Analysis of L21-ordering in full-Heusler Co2FeSi alloy thin films formed by rapid thermal annealing
• Epitaxial film growth and magnetic properties of Co_2FeSi
• Structural, magnetic and transport properties of thin films of the Heusler alloy Co2MnSi
• Unconventional one-magnon scattering resistivity in half metals
• Evolution of ferromagnetic and spin-wave resonances with crystalline order in thin films of full-Heusler alloy Co2MnSi
• Hall effect in laser ablated Co_2(Mn,Fe)Si thin films
• Formation of double ring patterns on Co2MnSi Heusler alloy thin film by anodic oxidation under scanning probe microscope

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