Exchange-spring mechanism and Griffiths-like phase in room-temperature magnetoelectric Ni–BaTiO₃ composites

Abstract

This is the first report on the occurrence of the exchange spring mechanism and a Griffiths-like phase in Ni–BaTiO3 magnetoelectric composites with 0–3 and 1–3 connectivity.

Exchange bias mediated self-biased magnetoelectric coupling in Co–BaTiO3 composites

“…This indirectly indicating the fact that the strain transfer and the ME coupling are prominent in the sample CP–BTO ratio 1 : 1 than CC–BTO ratio 1 : 1. 27 Also, we could notice a similar trend of variation in the separation of FCC and FCW data with the strength of ME coupling for Ni–BTO composites, 23 Ni@BTO core–shell structures 19,28 and Fe 3 O 4 –BTO composites. 29 Thus, the prominent observation of structural transitions in ME composites is attributed to the strong ME coupling and the large value of ME coupling coefficient.…”

“…In an earlier investigation, 23 we have observed exchange bias (EB) in the Ni-BTO composites due to the occurrence of AFM nickel oxide at the interface. In principle, EB refers to the unidirectional shift in the magnetic hysteresis of a ferro/ferrimagnetic material in contact with an antiferromagnetic (AFM) material.…”

“…Past reports advise that, the synthesis method, heat treatment, or particle size of the material can generate oxygen or titanium vacancies in BTO. 30–33 Duong et al and later Revathy et al reported the non-stoichiometry and oxygen vacancies in Ni–BTO systems, which are accountable for the diminution of the Ti 4+ oxidation state, 23,28,34 Furthermore, Rubavathi et al reviewed the effect of the ratio of Ba to Ti on the formation of Ti vacancies and found that the Ti deficiency is the source of weak FM nature of BTO. 35 Accordingly, a non-stoichiometric atomic percentage is formed for BTO content in the studied ME composites.…”

“…32 Hence, it is reasonable to assume that Co–BTO ME composites can form an interfacial cobalt oxide layer by attaching the O 2− and OH − groups on the surface of oxygen. 23,37 In short, there is chance for the presence of oxidation states like Co 0 , Co 2+ , Co 3+ and Co 4+ in Co–BTO composites. This means that there is finite possibility for the surface oxidation of cobalt to CoO, Co 3 O 4 , CoO 2 , Co 2 O 3 , or Co 2 O 4 .…”

Ultrasensitive Magneto electric Sensor based on Galfenol/ AlN structure

“…Frequency-selective and high-accuracy sensors in these categories of devices are so important for some specific applications which can be accessible in magnetic sensors based on magnetoelectric (ME) structures [14,15]. To get a large ME coefficient, nowadays, scientists use composites consisting of piezoelectric and magnetostrictive components in diverse configurations and three different types of 0-3-type particulate, 2-2-type laminates, and 1-3-type fiber composites [16][17][18].…”