Research/Sitter/MAGNDATA / 1.1.82_NpAs2.mcif

NpAs₂

MAGNDATA entry 1.1.82 · 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 ≤ 52 K (−221 °C)Colour: where that sits relative to 25 °C. Saturation: how much margin it has.

Structure · 11 properties

Magnetic group	Pmmn1′(α00)0s0s
Point group	mmm1′
Parent space group	P 4/n m m No. 129
Repeats every	7.09 cells along a (not a whole number: that's what incommensurate means)
Propagation	[0.141 0 0] 1k
Cell	a 3.958 · b 3.958 · c 8.098 Å · α 90° · β 90° · γ 90°
Transition	52 K (−221 °C)
Measured at	24.6 K
Magnetic ions	Np
Largest moment component	1.58 μ_B
Method	NSD

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 Pmmn1′(α00)0s0s →

Atom sites · 3 sites · CSV

site	element	x	y	z
As1	As	0.75	0.25	0
Np1	Np	0.25	0.25	0.281
As2	As	0.25	0.25	0.639

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

J. Rossat-Mignod et al. J. Magn. Magn. Mat. (1982) · doi:10.1016/0304-8853(82)90018-X

Cite the original paper and MAGNDATA, not this mirror.

Original file

⬇ 1.1.82_NpAs2.mcif from MAGNDATA · entry page

sha256 of this copy: 105cd4ff6f0857c73c9343b46d7248f68e037ab99bc76a74f3fd3bf765112819
The mirror keeps the bytes Bilbao served, so the original should hash the same unless MAGNDATA has revised the entry since: shasum -a 256 1.1.82_NpAs2.mcif.