Magnetic Structures Of Compounds Research Articles

Vibronic interaction as main reason of magnetic ordering in insulating manganites R1–xAxMnO3

The model of orbitally dependent magnetic structure of charge ordered insulated manganites is proposed. The model is semi-phenomenological. It allows using a few parameters to describe possible magnetic structures of compounds. The experimental crystal structure of compounds also could be taken into account. The compounds LaMnO3, La1/2Ca1/2MnO3, La1/3Ca2/3MnO3, BiMnO3 are considered.

Neutron structure analysis and magnetic properties of

The crystallographic and magnetic structures of compounds at room temperature were refined by Rietveld analysis of the neutron powder diffraction data. The analysis indicates that (x = 5,8) compounds have type structure . For x = 5 Ga atoms partially occupy 18h and 18f sites with the occupancies of 0.40 and 0.43, and for x = 8 they occupy 18h, 18f and 6c sites with the occupancies of 0.20, 0.80 and 1.0 respectively. The magneto-anisotropy changes from easy planar to easy-axial when the Ga content x increases from 5 to 8. The magnetic measurements show that the magnetic ordering temperature increases abnormally with Ga content x increasing from 6.5 to 8. This paper gives a reasonable explanation for this phenomenon.

Magnetic structures in compounds of the AFeCl 3 type: I

Possible configurations of the magnetic sublattice of the hexagonal compound AFeCl 3 (A = Rb, Cs) have been considered. The state ( k = 0) has been determined, which explains the abnormally large intermediate magnetization of this substance.

Magnetic structures in compounds of the AFeCl 3 type: II

Magnetic configurations ( k ≠ 0) of AFeCl 3 (A = Rb, Cs) compound have been found. Due to the change in the symmetry of the magnetic subsystem nonequivalent ions appear which possess ‘latent’ paramagnetism, i.e. the effective exchange field at these sites turns to zero. It has been shown that one of these states can explain the anomalous behaviour of magnetization in AFeCl 3.

Classification of magnetic structures in compounds with the Fe 2P-structure

A study is made of possible spin configurations in Fe 2P permitted by the symmetry considerations provided that the magnetic and crystallographic cells coincide. In the exchange approximation a number of magnetic structures is revealed. It is found that alongside with the standard ordering types: ferromagnetic (FM), ferrimagnetic (FIM), antiferromagnetic with the triangular spin lattice (AFM), there are non-trivial structures: antiferromagnetic-paramagnetic (AFM-PM) and antiferromagnetic-ferrimagnetic (AFM-FIM). The account of relativistic interactions leads to the upset of collinearity between the sublattice magnetic moments in the FM and FIM structures of the “easy-plane” type and in the basal plane of the AFM-FIM and AFM-PM structures. In the latter case a moment on the paramagnetic ion appears. These processes result in the change of the net moment and appearance of the weak ferromagnetic moment in the AFM-FIM and AFM-PM as well as in some AFM structures.

Umbrella‐Type Magnetic Structures in Diluted Ordered Lithium Ferrospinels

AbstractA symmetry analysis of ferrimagnetic structures is carried out in spinels that are isostructural with ordered lithium ferrite. The decrease of crystal symmetry due to the formation of atomic superstructure is shown to be a condition for realization of umbrella‐type magnetic structures in compounds of this class. The neutron diffraction data for lithium‐aluminium and lithium‐gallium ferrospinels are given which confirm the results of the theoretical treatment.