Research/Sitter/MAGNDATA / 1.1.55_CeCu2Ge2.mcif

CeCu₂Ge₂

MAGNDATA entry 1.1.55 · source

incommensurate spiral

Incommensurate: the magnetic pattern repeats every so many cells, but not a whole number of them, so it never lines up with the crystal lattice. Here it's a spiral: the spin direction rotates as you move along.

ordered ≤ 4.1 K (−269 °C)Colour: where that sits relative to 25 °C. Saturation: how much margin it has.

Structure · 11 properties

Magnetic group	I21′(α,α,γ)0s
Point group	21′
Parent space group	I 4/m m m No. 139
Repeats every	1.85 cells along c (not a whole number: that's what incommensurate means)
Propagation	[0.28 0.28 0.54] 1k
Cell	a 4.158 · b 4.158 · c 10.227 Å · α 90° · β 90° · γ 90°
Transition	4.1 K (−269 °C)
Measured at	1.5 K
Magnetic ions	Ce
Largest moment component	0.65 μ_B
Method	NPD

Symmetry

Stereogram of the magnetic point group: each operation applied to one direction. Filled = upper hemisphere, ring = lower; red operations include time reversal. Lines are mirrors; polygons are 2/3/4/6-fold axes; the centre ring is inversion.

Every structure in I21′(α,α,γ)0s →

Atom sites · 4 sites · CSV

site	element	y	z
Ce1	Ce	0	0
Cu1_1	Cu	0.5	0.25
Cu1_2	Cu	−0.5	−0.25
Ge1	Ge	0	0.385

Incommensurate: the moments are modulated; the picture evaluates each atom's Fourier series at its own phase.

Moment components are along the crystal axes a, b, c (μ_B), as magCIF writes them. Symmetry generates the rest of the cell from these sites.

Source

G. Knopp et al. Z. Phys. B - Condensed Matter (1989) · doi:10.1007/BF01313625

Cite the original paper and MAGNDATA, not this mirror.

Original file

⬇ 1.1.55_CeCu2Ge2.mcif from MAGNDATA · entry page

sha256 of this copy: 9eff65c3f4b73aa2cbbd2cb5641eee267c34405b795ce7980921b17b1bd1da1a
The mirror keeps the bytes Bilbao served, so the original should hash the same unless MAGNDATA has revised the entry since: shasum -a 256 1.1.55_CeCu2Ge2.mcif.