Manganese germanide

Manganese germanide (MnGe) is an intermetallic compound, a germanide of manganese. Its crystals have a cubic symmetry with no inversion center, they are therefore helical, with right-hand and left-handed chiralities.[1]

Manganese germanide

Structures of left-handed and right-handed MnGe crystals (3 presentations, with different numbers of atoms per unit cell; orange atoms are Ge)
Names
IUPAC name Manganese germanide
Identifiers
CAS Number	59125-33-6
3D model (JSmol)	Interactive image
PubChem CID	57481451
CompTox Dashboard (EPA)	DTXSID70851985
InChI InChI=1S/Mn.Ge Key: WWFYEXUJLWHZEX-UHFFFAOYSA-N
SMILES [Mn].[Ge]
Properties
Chemical formula	MnGe
Molar mass	127.57 g/mol
Magnetic susceptibility (χ)	2.17×10^−6 emu/g[1]
Structure
Crystal structure	Cubic[1]
Space group	P213 (No. 198), cP8
Lattice constant	a = 0.4795 nm
Formula units (Z)	4
Hazards
Flash point	Non-flammable
Related compounds
Other anions	Manganese silicide
Other cations	Iron germanide Cobalt germanide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Magnetism

Experimental phase diagram of MnSi_1-xGe_x alloys, revealing magnetic skyrmion, tetrahedral and cubic hedgehog spin arrangements at different compositions x.

At low temperatures, MnGe and its relative MnSi exhibit unusual spatial arrangements of electron spin, which were named magnetic skyrmion, tetrahedral and cubic hedgehog lattices. Their structure can be controlled not only by the Si/Ge ratio, but also by temperature and magnetic field. This property has potential application in ultrahigh-density magnetic storage devices.[2]

Synthesis

MnGe crystals can be produced by processing a mixture of Mn and Ge powders at a pressure of 4–5 GPa and a temperature of 600–1000 °C for 1–3 hours. They are metastable and decompose into Mn₁₁Ge₈ and Ge upon subsequent heating to 600 °C at ambient pressure.[1]

Structure

Manganese germanide is a non-stoichiometric compound where the Ge:Mn ratio often deviates from 1. The Mn₃Ge₅ compound is a Nowotny phase exhibiting a chimney ladder structure. It is either a semimetal or a narrow-gap semiconductor.[3]

References

1. Takizawa, H.; Sato, T.; Endo, T.; Shimada, M. (1988). "High-pressure synthesis and electrical and magnetic properties of MnGe and CoGe with the cubic B20 structure". Journal of Solid State Chemistry. 73 (1): 40–46. doi:10.1016/0022-4596(88)90051-5.
2. Nagaosa, Naoto; Tokura, Yoshinori (2013). "Topological properties and dynamics of magnetic skyrmions". Nature Nanotechnology. 8 (12): 899–911. doi:10.1038/nnano.2013.243.
3. Takizawa, H.; Sato, T.; Endo, T.; Shimada, M. (1987). "High-pressure synthesis and electrical properties of Mn₃Ge₅ with Mn₁₁Si₁₉-type structure". Journal of Solid State Chemistry. 68 (2): 234–238. doi:10.1016/0022-4596(87)90308-2.