Spin density wave order and fluctuations in ${\mathrm{Mn}}_3\mathrm{Si}$ : A transport study

We present a comprehensive transport investigation of the itinerant antiferromagnet ${\mathrm{Mn}}_3\mathrm{Si}$ which undergoes a spin density wave (SDW) order below $T_N\sim 21.3\mathrm{K}$. The electrical resistivity, the thermal conductivity, and the Hall, Seebeck, and Nernst effects exhibit pronounced anomalies at the SDW transition. At temperatures higher than $T_N$ our data provide strong evidence for a large fluctuation regime which extends up to $\sim 200\mathrm{K}$ in the resistivity, the Seebeck effect, and the Nernst effect. From the comparison of our results with other prototype SDW materials, viz., LaFeAsO and chromium, we conclude that many of the observed features are of generic character.

Figure 1

(a) Specific heat, (b) resistivity, (d) thermal conductivity, (c) Hall, (e) Seebeck, and (f) Nernst coefficient of ${\mathrm{Mn}}_3\mathrm{Si}$. Inset (a): construction of $T_N$. Inset (b): resistivity of LaFeAsO from Hess et al. [47]. Inset (c): transverse resistivity ${\rho }_{xy}$ vs magnetic field. Inset (d): $\kappa /T$, $L/\rho$, and $\kappa /T-L/\rho$ on a log scale. Inset (e): $S/T$. Inset (f): Nernst signal $e_y$ vs magnetic field.

Figure 2

Derivation of the resistivity of ${\mathrm{Mn}}_3\mathrm{Si}$(dots). Inset: resistivity deviation from the extrapolated high-temperature behavior $\rho -{\rho }_{\mathrm{extr}}$ (dots) solid line marks the temperature $55\mathrm{K}$ with maximum deviation.

Figure 3

Nernst coefficient $\nu /T$ of ${\mathrm{Mn}}_3\mathrm{Si}$(dots). Inset: Nernst coefficient plotted with a constant line at $\nu =0$.

Figure 4

Calculated one-band mobility $\mu$ of ${\mathrm{Mn}}_3\mathrm{Si}$(dots).