#\#CIF_2.0
# Created by the Bilbao Crystallographic Server
# http://www.cryst.ehu.es
# Date: 11/19/2017 17:14:36
# Database entry: 1.125 LaFeAsO
# Cif-like file for the case 1.125


data_5yOhtAoR
_audit_creation_date            2017-11-19
_audit_creation_method          "Bilbao Crystallographic Server"

_chemical_name_systematic
;
;
_chemical_name_common                    ?
_chemical_formula_moiety                 ?
_chemical_formula_structural             ?
_chemical_formula_analytical             ?
_chemical_formula_iupac                  ?
_chemical_formula_sum                    'La Fe As O'
_chemical_formula_weight                 ?
_chemical_melting_point                  ?
_chemical_compound_source                ?
_chemical_absolute_configuration         .


_citation_journal_abbrev        "PHYSICAL REVIEW B"
_citation_journal_volume        82
_citation_page_first            ?
_citation_page_last             ?
_citation_article_id            .
_citation_year                  184521
_citation_DOI                   10.1103/PhysRevB.82.184521

loop_
_citation_author_name
"N. Qureshi"
"Y. Drees"
"J. Werner"
"S. Wurmehl"
"C. Hess"
"R. Klingeler"
"B. Buchner"
"M.T. Fernandez-Diaz"
"M. Braden"




_atomic_positions_source_database_code_ICSD   180434
_atomic_positions_source_other               .

_transition_temperature     135
_experiment_temperature     2

loop_
_irrep_id
_irrep_dimension
_irrep_small_dimension
_irrep_direction_type
_irrep_action
_irrep_modes_number
_irrep_presence
mT4+ 1 1 . primary 1 .

_exptl_crystal_magnetic_properties_details
;
NPD
At Ts=152K (above TN) the structure changes from P4/nmm to Cmme
;

_active_magnetic_irreps_details
;
1k magnetic structure
k-maximal magnetic symmetry
1-dim irrep active, i.e. equivalence between MSG and irrep constraints
If the tetragonal phase were taken as parent, the observed spin ordering (propagation vector (1/2,1/2,1/2) in the tetragonal setting) would be sufficient to break the symmetry into the observed magnetic space group. This means that  the Cmme distortion of the nuclear structure is strongly coupled through a term that is quadratic in the magnetic order parameter and linear in the structural distortion.
;

_parent_space_group.name_H-M_alt  'C  m  m  e'
_parent_space_group.IT_number                       67
_parent_space_group.transform_Pp_abc  'a,b,c;0,0,0'

loop_
_parent_propagation_vector.id
_parent_propagation_vector.kxkykz
k1 [1 0 1/2]

_parent_space_group.child_transform_Pp_abc  'a,b,2c;0,0,0'
_space_group_magn.transform_BNS_Pp_abc  'a,b,c;0,0,0'


_space_group_magn.number_BNS  73.553
_space_group_magn.name_BNS  "I_c  b  c  a"
_space_group_magn.point_group_name  "mmm1'"
_space_group_magn.point_group_number  "8.2.25"
_cell_length_a                 5.7063(4)
_cell_length_b                 5.6788(4)
_cell_length_c                 17.419(1)
_cell_angle_alpha              90.00
_cell_angle_beta               90.00
_cell_angle_gamma              90.00

loop_
_space_group_symop_magn_operation.id
_space_group_symop_magn_operation.xyz
1 x,y,z,+1
2 x,-y,-z+1/2,+1
3 -x+1/2,y,-z,+1
4 -x,-y+1/2,z,+1
5 -x,-y,-z,+1
6 -x,y,z+1/2,+1
7 x+1/2,-y,z,+1
8 x,y+1/2,-z,+1

loop_
_space_group_symop_magn_centering.id
_space_group_symop_magn_centering.xyz
1 x,y,z,+1
2 x+1/2,y+1/2,z+1/2,+1
3 x,y,z+1/2,-1
4 x+1/2,y+1/2,z,-1

loop_
_atom_site_label
_atom_site_type_symbol
_atom_site_fract_x
_atom_site_fract_y
_atom_site_fract_z
_atom_site_occupancy
La1 La 0.00000 0.25000 0.071(2) 1
As1 As 0.00000 0.25000 0.32525(25) 1
Fe1 Fe 0.25000 0.00000 0.25000 1
O1 O 0.25000 0.00000 0.00000 1

loop_
_atom_site_moment.label
_atom_site_moment.crystalaxis_x
_atom_site_moment.crystalaxis_y
_atom_site_moment.crystalaxis_z
_atom_site_moment.symmform
Fe1 0.63(1) 0.0 0.0 mx,0,0

