Data-driven design of a new class of rare-earth free permanent magnets

Revealing the Magnetic Structure and Properties of Mn(Co,Ge)2

“…The calculations done previously assumed a temperature of T = 0 K, which explains the discrepancy. The Co moments recovered from the model of the incommensurate structure at 1.8 K are, however, very close to the calculated ones in the previous study . At 200 K, the magnetic moments of Co are similar to the 0.75 μ B reported for the cubic Heusler phase of Co 2 MnGe, likely making the discrepancy an effect of temperature in the calculations.…”

“…In order to investigate the magnetic structure of the system, it is necessary to first establish the atomic structure. Examination of the NPD data collected at 396 K, well into the paramagnetic regime, revealed several peaks that could not be indexed using the unit cell reported previously . A unit cell with parameters a = 9.5932(2) Å and c = 7.7440(2) Å using the same space group ( P 6 3 / mmc ) was able to describe the additional peaks.…”

“…4 This ordering also likely explains the discrepancy seen for the calculated structure in the recent study of the system. 3 It should be noted that the rather similar Laves systems of Mn− Cu−Si and Mn−Ni−Si, measured by room temperature NPD, did not show any indication of additional crystallographic ordering, instead maintaining the smaller MgZn 2 -type structures. 43 The moments of Co and Mn were predicted to achieve values of 1.56−1.59 and 3.28 μ B , respectively.…”

“…In the previous study, the sudden decrease in the magnetization versus temperature curve, marked in Figure 4a as T SRT,DC = 193 K, was suggested to be the onset of an incommensurate antiferromagnetic (AF) cone structure. 3 The AC magnetization results shown in Figure 4b,d suggest that this onset of the incommensurate structure occurs at a slightly lower temperature. First, the temperature dependence of the in-phase component of the AC magnetization shown in Figure 4b resembles the temperature dependence of the DC magnetization.…”

“…This has motivated research into finding materials that can replace RE magnets where the superior properties of the RE magnets are less critical, the so-called “gap magnets” which have properties somewhere between those of the RE magnets and the ferrite-based magnets . By use of data-mining and electronic structure calculations, several RE-free magnetic systems were recently proposed, and one candidate, Mn 2 Co 3 Ge, was successfully synthesized …”