Research/Sitter/MAGNDATA / 0.56_Ba2CoGe2O7.mcif

Ba₂CoGe₂O₇

MAGNDATA entry 0.56 · source

g-wave altermagnet

No net magnetisation, yet the electron bands are spin-split: the up and down spin sublattices are related only by a rotation or mirror, never by a shift or inversion. g-wave: 4 nodal planes.

Spin group ¹4/¹m²m²m: each symmetry marked ¹ keeps every spin, ² swaps up and down.

ordered ≤ 6.7 K (−266 °C)Colour: where that sits relative to 25 °C. Saturation: how much margin it has.

Structure · 11 properties

Magnetic group	C m′ m 2′ BNS 35.167
Point group	m′m2′
Parent space group	P 42₁m No. 113
Spins	collinear · 4 nodal planes · net moment 0 μ_B per cell
Propagation	[0 0 0] 1k
Cell	a 8.466 · b 8.466 · c 5.445 Å · α 90° · β 90° · γ 90°
Transition	6.7 K (−266 °C)
Measured at	2.2 K
Magnetic ions	Co
Largest moment component	2.05 μ_B
Method	Co moment 2.9(1). Moment components given with non-significant digits to yield this modulus approx.

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 C m′ m 2′ →

Atom sites · 11 sites · CSV

site	element	x	y	z	m_a	m_b	m_c	\|m\| (μ_B)
Ba_1	Ba	0.8346	0.3347	0.5077
Ba_2	Ba	0.3346	0.1654	0.4924
Co	Co	0	0	0	2.05	2.05	0	2.8991
Ge_1	Ge	0.6407	0.1407	0.9598
Ge_2	Ge	0.1407	0.3593	0.0402
O1_1	O	0	0.5	0.1594
O1_2	O	0.5	0	0.8406
O2_1	O	0.6379	0.1379	0.2705
O2_2	O	0.1379	0.3621	0.7296
O3_1	O	0.0791	0.1845	0.1886
O3_2	O	0.1845	0.9209	0.8114

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

V. Hutanu et al. PHYSICAL REVIEW B (2012) · doi:10.1103/physrevb.86.104401

Cite the original paper and MAGNDATA, not this mirror.

Original file

⬇ 0.56_Ba2CoGe2O7.mcif from MAGNDATA · entry page

sha256 of this copy: 12f79673177fdf4b4fa8c2802e50235ea1a90a20ce93fc0b46b9baa07d03b6db
The mirror keeps the bytes Bilbao served, so the original should hash the same unless MAGNDATA has revised the entry since: shasum -a 256 0.56_Ba2CoGe2O7.mcif.