Research/Sitter/MAGNDATA / 1.1.108_Cr2BeO4.mcif

Cr₂BeO₄

MAGNDATA entry 1.1.108 · 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 ≤ 28 K (−245 °C)Colour: where that sits relative to 25 °C. Saturation: how much margin it has.

Structure · 11 properties

Magnetic group	P2₁nm1′(0,0,γ)0s0s
Point group	mm21′
Parent space group	P b n m No. 62
Repeats every	11.49 cells along c (not a whole number: that's what incommensurate means)
Propagation	[0 0 0.087] 1k
Cell	a 4.555 · b 9.792 · c 5.663 Å · α 90° · β 90° · γ 90°
Transition	28 K (−245 °C)
Measured at	4.2 K
Magnetic ions	Cr
Largest moment component	2.75 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 P2₁nm1′(0,0,γ)0s0s →

Atom sites · 11 sites · CSV

site	element	x	y	z
Cr1_1	Cr	0	0	0
Cr2_1	Cr	0.495	0.232	0.75
Cr2_2	Cr	0.005	0.732	0.75
Be1_1	Be	−0.069	0.406	0.75
Be1_2	Be	0.569	−0.094	0.75
O1_1	O	0.277	0.407	0.75
O1_2	O	0.223	−0.093	0.75
O2_1	O	0.731	0.061	0.75
O2_2	O	0.769	0.561	0.75
O3_1	O	0.257	0.162	0.022
O3_2	O	0.243	0.662	0.478

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

D. E. Cox et al. JOURNAL OF APPLIED PHYSICS (1969) · doi:10.1063/1.1657557

Cite the original paper and MAGNDATA, not this mirror.

Original file

⬇ 1.1.108_Cr2BeO4.mcif from MAGNDATA · entry page

sha256 of this copy: 6a1e1e9a4eddd83cd2b2a1e3ed48d2ecee2faec2e745c47b365f236981d847a2
The mirror keeps the bytes Bilbao served, so the original should hash the same unless MAGNDATA has revised the entry since: shasum -a 256 1.1.108_Cr2BeO4.mcif.