Research/Sitter/MAGNDATA / 1.1.164_BiFeO3.mcif

BiFeO₃

MAGNDATA entry 1.1.164 · 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 ≤ 643 K (370 °C)Colour: where that sits relative to 25 °C. Saturation: how much margin it has.

Structure · 11 properties

Magnetic group	Cc1′(0,0,γ)0s
Point group	m1′
Parent space group	R 3 c No. 161
Repeats every	222.22 cells along a (not a whole number: that's what incommensurate means)
Propagation	[0.0045 0.0045 0] 1k
Cell	a 5.5775 · b 5.5775 · c 13.8616 Å · α 90° · β 90° · γ 120°
Transition	643 K (370 °C)
Measured at	293 K
Magnetic ions	Fe
Largest moment component	4.05 μ_B
Method	Single-crystal polarized small-angle neutron scattering

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 Cc1′(0,0,γ)0s →

Atom sites · 5 sites · CSV

site	element	x	y	z
Bi1_1	Bi	0	0	0.7792
Fe1_1	Fe	0	0	0
O1_1	O	0.4473	0.0198	0.7317
O1_2	O	0.9802	0.4275	0.7317
O1_3	O	0.5725	0.5527	0.7317

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

M Ramazanoglu et al. Phys. Rev. Lett. (2011) · doi:10.1103/PhysRevLett.107.207206

Cite the original paper and MAGNDATA, not this mirror.

Original file

⬇ 1.1.164_BiFeO3.mcif from MAGNDATA · entry page

sha256 of this copy: 65c922402d6d76be98d386f9cf153471de3e58c69c6944488942908a45a8e520
The mirror keeps the bytes Bilbao served, so the original should hash the same unless MAGNDATA has revised the entry since: shasum -a 256 1.1.164_BiFeO3.mcif.