Surface segregation in multicomponent magnetic Bismuth ferrite nanoparticles

Abstract Surface segregation is a ubiquitous phenomenon driven by minimization of the total free energy. In this paper we study surface segregation in multicomponent magnetic Bismuth ferrite nanoparticles alloyed with varying amounts of Dysprosium, Zinc and Titanium. We employ surface and bulk sensitive spectroscopic probes to unravel a significant surface segregation of Bismuth oxide and Titanium oxide. High coercive fields of BiFe 0.95 Ti 0.05 O 3 (BFTO) and BiFe 0.96 (Zn, Ti) 0.02 O 3 (BFZTO) at room temperature reveal that they have a strong exchange bias. This suggests that the Titanium oxide is magnetically active, and there is a Ti induced d o ferromagnetism in action between these nanoparticles. We show, with the addition of Dy 2 O 3 , the Ti induced d o ferromagnetism is suppressed making (BDFZTO) superparamagnetic. We observe that all three differently alloyed Bismuth ferrite nanoparticles show a non-saturating paramagnetic background.