Ambient Pressure Synthesis of Re-Substituted MnGe and Its Magnetic Properties

Abstract

Due to their non-centrosymmetric structure, B20-type compounds have intriguing properties of chiral magnets and are the objects of study of topological spin textures. Among them is a high-pressure phase MnGe, which demonstrates properties of magnetic skyrmions. We report on the synthesis of an Mn1−xRexGe solid solution with the B20 structure, which can be prepared without the application of high pressure. Mn1−xRexGe (x = 0.169(6)) shows unconventional magnetic behavior, where the Neel temperature is only slightly reduced compared to a chiral-lattice helimagnet MnGe.

Impact of Ge Doping on Structural and Magnetic Ordering in RMnxGa3 and R4Mn1–xGa12–yGey (R = Tb, Dy; x ≤ 0.25, y ≈ 1.0–3.3)

“…The M ( H ) curves for 50 K and below show nonlinear behavior in low-applied fields, which confirms that the onset of the ferromagnetic ordering is in the region above 50 K. The ferromagnetic contribution to magnetization continues to increase upon further cooling up to 25 K in both cases, where it reaches similar values of about 0.5–0.6 μ B per formula unit or 2.5–3 μ B per Mn atom. The latter values are in a typical range for a saturation magnetic moment of Mn atoms in intermetallic compounds, where it can vary from about 1 μ B in Mn 1– x Re x Ge , and 1.5 μ B in Y 4 Mn 1– x Ga 12– y Ge y , to 2.5 μ B in τ-MnAl and Mn 1– x Ga x , and ∼4 μ B in Cu 2 MnIn . However, as it will be demonstrated in the next section, the saturation magnetization in low fields might contain a large contribution from the rare earth ordered moments even above T N .…”

Itinerant ferromagnet Re4−xMnxGe7−δ (x = 0.9–1.5, δ = 0.42–0.44) with incommensurate chimney-ladder structure stabilised at ambient pressure

“…Recently, we successfully used this approach to stabilise the related high-pressure phase MnGe by replacing 16-20% of Mn atoms by Re. 26 As a side-product of the synthesis, we also observed an unknown phase, diffraction pattern of which was reminiscent of both Re 4 Ge 7 16 and Mn 3 Ge 5 . 15 Our study shows that this phase is a new ternary chimneyladder compound Re 4−x Mn x Ge 7−δ (x = 0.9-1.5 δ = 0.42-0.44), which is an ambient-pressure derivative of Mn 3 Ge 5 and Re 4 Ge 7 high-pressure phases.…”

“…Recently, we successfully used this approach to stabilise the related high-pressure phase MnGe by replacing 16–20% of Mn atoms by Re. 26 As a side-product of the synthesis, we also observed an unknown phase, diffraction pattern of which was reminiscent of both Re 4 Ge 7 16 and Mn 3 Ge 5 . 15…”

“…It is also worth noting that the magnetic behaviour of Re 4−x Mn x Ge 7−δ is similar in some aspects to that of another ternary Re-Mn-Ge compound, Mn 1−x Re x Ge, which demonstrates high coercivity around 5 kOe and close values of Mn magnetic moment (1μ B ) and Tc (150 K). 26 However, the magnetisation of Mn 1−x Re x Ge grows very slowly with the magnetic field, whereas magnetic moments in Re 4−x Mn x Ge 7−δ become almost fully saturated at 30 kOe. Given that the structurally related phases do not demonstrate high coercivity in the cases for both Re 4−x Mn x Ge 7−δ and Mn 1−x Re x Ge, 14,15,22,39 it can be assumed that Re atoms should play a role in it.…”