Beyond Germanides: Anomalous Hall Effect in the Silicide LaMn2Si2

TL;DR

The paper investigates the anomalous Hall effect in the silicide family $RMn_2Si_2$, focusing on the noncollinear LaMn_2Si_2 with a magnetic space group $Im'm2'$. Using first-principles calculations with spin-orbit coupling and Wannier-based Kubo formalism, it predicts a substantial intrinsic AH conductivity $\sigma^{AH}_{xy} \approx -365$ S/cm, with much smaller off-diagonal components. Symmetry considerations show that this material should host a finite AH response, and electron doping by about 0.4 electrons per formula unit can enhance $|\sigma^{AH}_{xy}|$ toward about 650 S/cm, indicating tunability. The work highlights silicides with the $ThCr_2Si_2$ structure as platforms for anomalous Hall transport and related spintronic phenomena, and suggests further exploration of similar materials and potential topological features in quasi-2D limits.

Abstract

By combining symmetry analysis and direct density functional calculations including the spin-orbit coupling, we demonstrate that anomalous Hall effect can be observed in not only germanides with general formula RMn$_2$Ge$_2$, where $R$ is a rare-earth ion or Y. Our calculations predict a large anomalous Hall conductivity in LaMn$_2$Si$_2$, with a non-zero $σ_{xy}^{AH}$ component of $-360~\text{S/cm}$, accompanied by a pronounced magneto-optical response. Remarkably, electron doping of LaMn$_2$Si$_2$ is expected to substantially enhance the Hall conductivity, with values reaching up to -650 S/cm. These results suggest that silicides with general formula RM$_2$Si$_2$ can be an interesting platform for studying anomalous Hall effect.

Figures (6)

• Figure 1: Crystal and magnetic structure of LaMn$_2$Si$_2$. Figure was plotted using VESTA VESTA.
• Figure 2: Band structure as obtained in GGA and GGA+SOC calculations (a). Berry curvature $\Omega_{xy}$ along high-symmetry directions (b). The Fermi energy is at zero. Blue dashed lines show points along chosen path contributing the most to $\Omega_{xy} ({\bf k})$.
• Figure 3: GGA+SOC electronic band structure of LaMn$_2$Si$_2$ with $x$ projection of spin shown by color. The Fermi energy is set to zero. Inset shows k-points used for the band plotting.
• Figure 4: Total density of states (DOS) as obtained in GGA+SOC calculations. The Fermi energy is set to zero.
• Figure 5: Intrinsic anomalous Hall conductivity $\sigma^{AH}_{xy}$ as function of the Fermi energy variation. Zero $\delta E_F$ corresponds to the actual Fermi level in LaMn$_2$Si$_2$.