Antisite disorder and Berry curvature driven anomalous Hall effect in the spin gapless semiconducting Mn2CoAl Heusler compound

Abstract

Spin gapless semiconductors exhibit a finite band gap for one spin channel and a closed gap for another spin channel, and they have emerged as a new state of magnetic materials with a great potential for spintronic applications. The first experimental evidence for spin gapless semiconducting behavior was observed in an inverse Heusler compound Mn 2 CoAl. Here, we report a detailed investigation of the crystal structure and anomalous Hall effect in Mn 2 CoAl using experimental and theoretical studies. The analysis of the high-resolution synchrotron x-ray diffraction data shows antisite disorder between Mn and Al atoms within the inverse Heusler structure. The temperature-dependent resistivity shows semiconducting behavior and follows Mooij's criteria for disordered metal. The scaling behavior of the anomalous Hall resistivity suggests that the anomalous Hall effect in Mn 2 CoAl is primarily governed by an intrinsic mechanism due to the Berry curvature in momentum space. The experimental intrinsic anomalous Hall conductivity (AHC) is found to be ∼35 S/cm, which is considerably larger than the theoretically predicted value for ordered Mn 2 CoAl. Our first-principles calculations conclude that the antisite disorder between Mn and Al atoms enhances the Berry curvature and hence the value of intrinsic AHC, which is in very good agreement with the experiment.

Spin-gapless semiconducting characteristics and related band topology of quaternary Heusler alloy CoFeMnSn

“…The negative value of coefficients ( a , b ) signifies that extrinsic skew scattering contribution is in the opposite direction to both side-jump and intrinsic contribution due to momentum space Berry curvature, resulting in a lower total AHC which is almost equal to half of the theoretically predicted intrinsic contribution. Similar features have been also observed for other SGSs, 60,62 FeRhCrGe 53 and MnGa. 63…”

“…The half-metallic systems have a larger number of majority spin states and a finite minority spin channel gap as compared to SGS compounds, which leads to a larger intrinsic AHC. 59,60 In order to verify the SGS characteristics of CoFeMnSn, the hall conductivity has been measured at different temperatures. The σ xy at 5 K is presented in Fig.…”

CoMnCrGa: a novel ferromagnetic material with high spin-polarization for room temperature spintronics

“…The AHC arising from the side jump mechanism can be approximated using the expression e 2 ha Á E so E F where E so represents the spin-orbit interaction energy, and E F is the Fermi Paper Journal of Materials Chemistry C energy. 68,69 It is worth noting that E so E F is typically less than 0.01 for ferromagnetic metals, indicating that the intrinsic Berryphase-driven contribution predominantly governs the AHC, which is also evident from Fig. 12(c).…”