Research/Sitter/MAGNDATA / 1.1.87_CaCr2O4.mcif

CaCr₂O₄

MAGNDATA entry 1.1.87 · 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 ≤ 43 K (−230 °C)Colour: where that sits relative to 25 °C. Saturation: how much margin it has.

Structure · 11 properties

Magnetic group	P2₁2₁21′(0β0)000s
Point group	2221′
Parent space group	Pmmn No. 59
Repeats every	3 cells along b (not a whole number: that's what incommensurate means)
Propagation	[0 0.333 0] 1k
Cell	a 11.059 · b 5.836 · c 5.114 Å · α 90° · β 90° · γ 90°
Transition	43 K (−230 °C)
Measured at	6 K
Magnetic ions	Cr
Largest moment component	2.58 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 P2₁2₁21′(0β0)000s →

Atom sites · 8 sites · CSV

site	element	x	y	z
Ca1	Ca	0.25	0.75	0.1481
Ca2	Ca	0.75	0.75	0.4648
Cr1	Cr	−0.0078	0.25	0.4942
Cr2	Cr	0	0	0
O1	O	0.594	0.25	0.162
O2	O	0.409	0.25	0.821
O3_1	O	0.402	0.497	0.33
O3_2	O	−0.402	−0.497	−0.33

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

S. Toth et al. PHYSICAL REVIEW B (2011) · doi:10.1103/PhysRevB.84.054452

Cite the original paper and MAGNDATA, not this mirror.

Original file

⬇ 1.1.87_CaCr2O4.mcif from MAGNDATA · entry page

sha256 of this copy: 2b52d98620b0d2fe6496160af6611aab5b04fdd53d00cd26c82e288c17ad4644
The mirror keeps the bytes Bilbao served, so the original should hash the same unless MAGNDATA has revised the entry since: shasum -a 256 1.1.87_CaCr2O4.mcif.