The magnetism of the $M_{n+1}A{X}_n$ phase, ${\text{Cr}}_2$GeC, and its Mn-doped system, (${\text{Cr}}_{1-x}$${\text{Mn}}_x$)${}_2$GeC ($x\le 0.25$), synthesized via a solid state reaction, was investigated systematically. ${\text{Cr}}_2$GeC is in a spin-unpolarized state, but the ferromagnetic band polarization is induced immediately by the Mn doping. The Curie temperature, $T_{\mathrm{C}}$, and the spontaneous moment, $p_{\mathrm{s}}$, increase almost proportionally to the Mn concentration, strongly suggesting that ${\text{Cr}}_2$GeC is located in the vicinity of a ferromagnetic quantum critical point. The strong concentration dependence of $p_{\mathrm{eff}}/p_{\mathrm{s}}$, where $p_{\mathrm{eff}}$ is the effective moment in the paramagnetic state, indicates that the ferromagnetism appearing in the Mn-doped ${\text{Cr}}_2$GeC can be classified as a typical itinerant-electron ferromagnetism in a wide range of the degree of electron localization.

• Received 20 November 2013
• Revised 9 February 2014

DOI:https://doi.org/10.1103/PhysRevB.89.054435