Research/Sitter/MAGNDATA / 0.1080_Ca2Fe2O5.mcif

Ca₂Fe₂O₅

MAGNDATA entry 0.1080 · source

d-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. d-wave: the splitting changes sign twice around the Fermi surface (2 nodal planes).

Spin group ²m¹m²m: each symmetry marked ¹ keeps every spin, ² swaps up and down.

ordered ≤ 720 K (447 °C)Colour: where that sits relative to 25 °C. Saturation: how much margin it has.

Structure · 11 properties

Magnetic group	P n′ m′ a BNS 62.446
Point group	m′m′m
Parent space group	P c m n No. 62
Spins	collinear · 2 nodal planes · net moment 0 μ_B per cell
Propagation	[0 0 0] 1k
Cell	a 5.64 · b 14.68 · c 5.39 Å · α 90° · β 90° · γ 90°
Transition	720 K (447 °C)
Measured at	4.2 K
Magnetic ions	Fe
Largest moment component	4.5 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 P n′ m′ a →

Atom sites · 6 sites · CSV

site	element	x	y	z	m_a	m_b	m_c	\|m\| (μ_B)
Fe1	Fe	0	0	0	0	0	4.5	4.5
Fe2	Fe	0.928	0.25	0.945	0	0	−4.5	4.5
Ca1	Ca	0.028	0.112	0.48
O1	O	0.25	0.985	0.25
O2	O	0.055	0.133	0
O3	O	0.863	0.25	0.607

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

Takayoshi Takeda et al. J. Phys. Soc. Jpn. (1968) · doi:10.1143/JPSJ.24.446

Cite the original paper and MAGNDATA, not this mirror.

Original file

⬇ 0.1080_Ca2Fe2O5.mcif from MAGNDATA · entry page

sha256 of this copy: e199c5d97cd0fc61d5de092357bbf679fededcc4d0c95b22a3866e9b2555ff3e
The mirror keeps the bytes Bilbao served, so the original should hash the same unless MAGNDATA has revised the entry since: shasum -a 256 0.1080_Ca2Fe2O5.mcif.