Research/Sitter/MAGNDATA / 1.1.77_NiBr2.mcif

NiBr₂

MAGNDATA entry 1.1.77 · 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 ≤ 22.8 K (−250 °C)Colour: where that sits relative to 25 °C. Saturation: how much margin it has.

Structure · 11 properties

Magnetic group	Rm1′(ααγ)0s
Point group	m1′
Parent space group	R 3m No. 166
Repeats every	0.67 cells along c (not a whole number: that's what incommensurate means)
Propagation	[0.027 0.027 1.5] 1k
Cell	a 3.723 · b 3.723 · c 18.34 Å · α 90° · β 90° · γ 120°
Transition	22.8 K (−250 °C)
Measured at	4.2 K
Magnetic ions	Ni
Largest moment component	2 μ_B
Method	NSD and 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 Rm1′(ααγ)0s →

Atom sites · 3 sites · CSV

site	element	z
Ni1	Ni	0
Br1_1	Br	0.255
Br1_2	Br	−0.255

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. Adam et al. Solid State Communications (1980) · doi:10.1016/0038-1098(80)90757-7

Cite the original paper and MAGNDATA, not this mirror.

Original file

⬇ 1.1.77_NiBr2.mcif from MAGNDATA · entry page

sha256 of this copy: d8d0798c6f5753f9bb34f0d6bfc5b32c1d4b8f9a44da5029ebb241d6695539a2
The mirror keeps the bytes Bilbao served, so the original should hash the same unless MAGNDATA has revised the entry since: shasum -a 256 1.1.77_NiBr2.mcif.