Material, canted spin

Fig. 7.9. Schematic representation of the orientation of magnetic moments in ordered materials (a) ferromagnetics (b) antiferromagnetics (c) ferrimagnetics (d) canted spin materials.

Similar to ferrimagnets, canted antiferromagnets of uniform spin moments that cannot assume antiparallel orientations give rise to net moments as well. Examples for such materials are FeF3 or FeB03. 

Julve, Lloret, and co-workers have reported several isomorphous oxalate-based coordination polymers presenting magnet behaviour through spin canting below 40 and 70 K [108, 109]. Among them, the 3-D and chiral coordination polymer [Fe,(2) (OH)Cl ] EtNH -2H O is the most interesting. This material possesses helical... 

For nanoobjects, spin disorder often occurs when placed into Bext- If present, the behavior of A2,s deviate from that expected for bulk materials (with no spin disorder). A nonzero A2,s can be then used to quantify the degree of spin disorder (through spin canting under B xt) and determine the portion of disordered magnetic moments within a... 

Experimental determinations of for fine particles show some inconsistencies. This is not surprising, as detailed studies on ultrathin films have shown that changes may depend on several parameters. Generally, is lowered with respect to the saturation magnetization value for the corresponding bulk material. The decrease should be mainly due to spin canting at the surface, that is, disorientations of spins directions, as evidenced by Mossbauer spectroscopy experiments. " A decrease of the magnetic moment per spin at the surface is also possible for metallic particles. However, for the present it is difficult to predict such effects because of the lack of systematic studies on the different types of particles. 

Fig. 16.6. Two dimensional projection of probable spin alignments of amorphous lanthanide alloys (A) ferrimagnetic for Gd materials (e.g. GdFej) and (B), (C) canted ferrimagnetic for materials with lanthanide ions possessing a strong local anisotropy (e.g. TbFej) at 0 applied field (B) and finite field (C).

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