Research/Sitter/MAGNDATA / 1.1.91_PrCo2Ge2.mcif

PrCo₂Ge₂

MAGNDATA entry 1.1.91 · source

incommensurate spin-density wave

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 spin-density wave: the size of the spin swells and shrinks as you move along.

ordered ≤ 28 K (−245 °C)Colour: where that sits relative to 25 °C. Saturation: how much margin it has.

Structure · 11 properties

Magnetic group	I4/mmm1′(00γ)00sss
Point group	4/mmm1′
Parent space group	I 4/m m m No. 139
Repeats every	1.37 cells along c (not a whole number: that's what incommensurate means)
Propagation	[0 0 0.73] 1k
Cell	a 4.053 · b 4.053 · c 10.23 Å · α 90° · β 90° · γ 90°
Transition	28 K (−245 °C)
Measured at	4.2 K
Magnetic ions	Co, Pr
Largest moment component	3.98 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 I4/mmm1′(00γ)00sss →

Atom sites · 3 sites · CSV

site	element	y	z
Co1	Co	0.5	0.25
Ge1	Ge	0	0.374
Pr1	Pr	0	0

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

A. Szytula et al. Physica Status Solidi(a) (1980) · doi:10.1002/pssa.2210580107

Cite the original paper and MAGNDATA, not this mirror.

Original file

⬇ 1.1.91_PrCo2Ge2.mcif from MAGNDATA · entry page

sha256 of this copy: 6663e2e31633b6658bec44b8aafb182b7204af6b3a3829dbe95ab5289cc7991b
The mirror keeps the bytes Bilbao served, so the original should hash the same unless MAGNDATA has revised the entry since: shasum -a 256 1.1.91_PrCo2Ge2.mcif.