Antiferromagnetism canted

Plouet, M.R., Vilminot, S., Guillot, M. and Kurmoo, M. (2002) Canted antiferromagnetism in an organo-modified layered nickel phyllosilicate. Chemistry of Materials, 14, 3829—3836. 

LB deposition of the TTF-LBl amphiphile from an aqueous Mn+ subphase forms Y-type hlms with stoichiometry Mn2 (11L-LB1 )(H2 0)2. Static x measurements show that the hlms become magnetic near 11.5 K when the manganese phosphonate network orders as a canted antiferromagnet. This is illustrated in Fig. 6.44. 

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. 

Fig. 4 Comparison of generic FC and ZFC susceptibility versus temperature plots for a canted antiferromagnet (left) spontaneous magnetization in a canted antiferromagnet.

YC1O3 shows canted antiferromagnetism (7n = 140 K) and a dielectric anomaly like a ferroelectric at 473 K47 (Fig. 8). Dielectric hysteresis in YCrCb is like in leaky dielectrics with a small polarization... 

Canted Antiferromagnetism, Helimagnetism, and Other Noncollinear Orderings... 

The canted antiferromagnet shows ferromagnetic like behavior for the susceptibility and magnetization but can... 

Fig. 17. Schematic diagram of relative spin orientations in a canted antiferromagnet such as MnCOa...

Recent work in Versailles and Santa Barbara has led to the synthesis of several nanoporous nickel(II) phosphates. A zeolitic nickel(II) phosphate, VSB-1 (Versailles/Santa Barbara-1), was prepared under simple hydrothermal conditions [22] and has a unidimensional pore system delineated by 24 NiO and PO4 poly-hedra with a free diameter of approximately 0.9 nm (Figure 18.7). It becomes microporous on calcination in air at 350 °C, yielding BET surface areas up to 160 m g and is stable in air to approximately 500 °C. The surface area appears low compared with aluminosilicate zeolites, but the density of VSB-1 is twice that of a zeolite and the channel walls are particularly thick. VSB-1 can be prepared in both ammonium and potassium forms, and exhibits ion-exchange properties that lead, for example, to the formation of the lithium and sodium derivatives. Other cations (e.g. Mn, Fe, Co, and Zn) can be substituted for Ni in VSB-1, up to a level as high as 30 atomic%. The parent compound shows canted antiferromagnetic order at Tn = 10.5 K with 6 = —71 K on doping with Fe, Tn increases to 20 K and 6 decreases to —108 K. 

Figure 13. Model of self-reversal in the ilmenite-hematite solid solution (after Hoffman 1992). Boxes represent (001) cation layers (viewed down the c-axis), shaded according to their Fe-occupancy (Fe = dark, Ti = light). Two ordered ferrimagnetic domains are shown (left and right) separated by a twin wall (central) with a canted antiferromagnetic stmeture. (a) The twin wall orders first with its parasitic moment parallel to the external field. The ferrimagnetic domains order perpendicular to external field and antiparallel to each other, (b) The domain moments tilt away from the wall moment at lower temperatnres, creating a large reverse component of magnetization.

Other Kinds of Three-Dimensional Order Metamagnetism and Canted Antiferromagnetism... 

A completely separate phenomenon that happens also to occur in this compound is canted antiferromagnetism (also known as weak ferromagnetism). In the nominally antiferromagnetic state (i.e. below the critical field), anisotropy creates a situation in which antiparallel alignment of the spins is imperfect. Because the spins are vector quantities, a small nonzero angle between them results in incomplete cancellation (Figure 3.24b). This gives rise to a net moment that, in the case of [FeCp 2][DCNQ], is manifest as a tiny hysteresis loop centred about zero. 

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