Magnetic structure in Mn1−xCoxGe compounds

Theoretical and experimental study of high-pressure synthesized B20-type compounds Mn1− x (Co,Rh) x Ge

“…4). Similar practically linear a(x) curve has been already observed for Mn 1−x Co x Ge in papers [14,20]. The linear dependence a(x) has been also reported for other solid solutions of B20-type 3d-metal monogermanides: [11,21] and Fe 1−x Co x Ge [22].…”

“…The region [0.5 < x < 0.85; T C2 < T < T C1 ] is of special interest: although the SPH does not exist there, the double-peak shape of χ(T ) dependencies is preserved. In paper [14], the analysis of the experimental data for two compositions, Mn 0.4 Co 0.6 Ge and Mn 0.5 Co 0.5 Ge, has also demonstrated the presence of two-peak feature of SANS intensity in the temperature range from 5 K to 80 K. This feature has been described in [14] as consisting of main and satellite peaks. The authors [13], however, explain the second peak as a manifestation of the TGB phase.…”

“…9b that in the Mn-rich side (x < 0.25), a SPH with a period of ∼ 30Å exists in a wide range of temperatures up to 165 K (painted blue in the figure). Next interval of concentrations is 0.25 < x < 0.5, where a low-temperature SPH coexists with a LPH up to T C2 ∼ 40 K. Within this region, the helix period increases with x up to ∼ 120Å (see paper [14], where Fig. 10 displays the x-dependence of the helix wave vector Q measured at T = 5 K).…”

“…It should be noted that compositions belonging to the Mn-rich side (x ≤ 0.5) have been studied in [13] using the small-angle neutron scattering (SANS) and neutron powder diffraction techniques. More recently, the characterization of magnetic structure in Mn 1−x Co x Ge at 0 ≤ x ≤ 0.9 has been performed using the SQUID magnetometer and SANS measurements [14]. Here, we applied a more sensitive experimental technique, which allowed us to refine the shape of the χ(T ) dependencies [13], which are more than one order of magnitude larger than in pure MnGe and the Mn-rich side (x ≤ 0.25) of the Mn 1−x (Co,Rh) x Ge series [13,14].…”

Complex magnetism of B20-MnGe: from spin-spirals, hedgehogs to monopoles

“…The main finding from these works is that D is too small when combined with A to explain the experimentally observed short period of the magnetic structure, which is given by λ ≈ 4πA/D. Experimentally, the magnetic structure has been interpreted as consisting of helical spirals 21,[25][26][27]29 as in other B20 compounds, with the short period ascribed to competing long-range magnetic interactions 26,29 . Transport signatures and LTEM imaging strongly back a more complex magnetic structure, which has initially been interpreted as a conventional twodimensional skyrmion lattice 19,20,31,33 , and afterwards as a three-dimensional skyrmion-antiskyrmion or hedgehogantihedgehog lattice 28,30,32,35 .…”