Extraordinary enhancement of Néel transition temperature in nanoparticles of multiferroic tetragonal compositions of (1 − x)BiFeO3-xPbTiO3 solid solutions

Abstract

The Néel temperature (TN) in conventional antiferromagnets (AFM) decreases with decreasing particle size. In contrast, we present here evidence for an exotic facet of multiferroicity, whereby one can raise the TN by more than 200 K by decreasing the particle size. We illustrate this by taking the example of a tetragonal composition with x = 0.5 in the solid solutions of (1 − x)BiFeO3-xPbTiO3 (BF-xPT). We attribute it to the increase in the strength of the superexchange interaction via a decrease in the ferroelectric distortion in nanocrystalline powder of BF-0.5PT. The BF-0.5PT nanoparticles also exhibit exchange bias effect due to AFM core-FM shell type magnetic nanostructure.

Magnetic properties and B-site cation ordering in (Sr0.5Ba0.5)2FeSbO6 perovskite

“…From Figure 2 where we plot TN against the domain size it can be seen that the dependency is nearly linear. This linearity could suggest that TN in (Sr0.5Ba0.5)2FeSbO6 depends even more strongly on the ordereddomain size than the DoO parameter S. Similar magnetic-property dependencies on DoO and ordered-domain size have been seen for some multiferroic systems as well, but with an opposite effect on TN [31,32]. It should be mentioned that we made an effort to study the finite-size effect on TN.…”

Origin of low thermal hysteresis in shape memory alloy ultrathin films

“…Sun et al subsequently used this model to explain the small hysteresis in TiNi nanocrystals [21][22]. Nevertheless, experimental results in other phase transforming systems, such as ferroelectric nanofilms, have shown that the surface region can suppress the spontaneous transformation in a number of cases but can promote phase 4 transformation in others [23][24][25]. Thus, the open questions are (1) what is the hysteresis behavior in the case where the effects of the surface promotes phase transformation?…”