Research/Sitter/MAGNDATA / 1.1.56_CeAg2Si2.mcif

CeAg₂Si₂

MAGNDATA entry 1.1.56 · 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 ≤ 10 K (−263 °C)Colour: where that sits relative to 25 °C. Saturation: how much margin it has.

Structure · 11 properties

Magnetic group	Immm1′(α00)0sss
Point group	mmm1′
Parent space group	I 4/m m m No. 139
Repeats every	1.46 cells along a (not a whole number: that's what incommensurate means)
Propagation	[0.685 0 0] 1k
Cell	a 4.084 · b 4.084 · c 10.169 Å · α 90° · β 90° · γ 90°
Transition	10 K (−263 °C)
Measured at	4.2 K
Magnetic ions	Ce
Largest moment component	0.93 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 Immm1′(α00)0sss →

Atom sites · 3 sites · CSV

site	element	y	z
Ag1	Ag	0.5	0.25
Ce1	Ce	0	0
Si1	Si	0	0.3918

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

B.H. Grier et al. PHYSICAL REVIEW 8 (1984) · doi:10.1103/PhysRevB.29.2664

Cite the original paper and MAGNDATA, not this mirror.

Original file

⬇ 1.1.56_CeAg2Si2.mcif from MAGNDATA · entry page

sha256 of this copy: a25201f6f9d442abb27daf0a6f2cf13e95b1f86bb5880ef8c5699f68d841ff78
The mirror keeps the bytes Bilbao served, so the original should hash the same unless MAGNDATA has revised the entry since: shasum -a 256 1.1.56_CeAg2Si2.mcif.