Pandey, Himanshu and Budhani, R. C. (2013) Structural ordering driven anisotropic magnetoresistance, anomalous Hall resistance, and its topological overtones in full-Heusler Co2MnSi thin films. Journal of Applied Physics , 113 (20). 203918-1-203918-9. ISSN 0021-8979

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We report the evolution of crystallographic structure, magnetic ordering, and electronic transport in thin films of full-Heusler alloy Co2MnSi deposited on (001) MgO with annealing temperatures (T-A). By increasing the T-A from 300 degrees C to 600 degrees C, the film goes from a disordered nanocrystalline phase to B2 ordered and finally to the L2(1) ordered alloy. The saturation magnetic moment improves with structural ordering and approaches the Slater-Pauling value of approximate to 5.0 mu(B) per formula unit for T-A = 600 degrees C. At this stage, the films are soft magnets with coercive and saturation fields as low as approximate to 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 x 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 degrees C. We find maximum topological contribution to Hall resistivity around 0.5 T while it approach to zero with increasing magnetic field. The anisotropic magnetoresistance changes its sign from positive to negative as we go from as deposited to 600 degrees C annealed film, suggesting a gradual increase in the half-metallic character.

Item Type: Article
Additional Information: Copyright for this article belongs to M/s American Institute of Physics.
Subjects: Applied Physics/Condensed Matter
Depositing User: Users 27 not found.
Date Deposited: 09 Jun 2020 10:01
Last Modified: 09 Jun 2020 10:01

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