Sea urchin-like Ni encapsulated with BaTiO3 to form multiferroic core-shell structures for room temperature magnetoelectric sensors

Highlights: : • The first report on the encapsulation of sea urchin-like Ni nanoparticles using BaTiO₃ nanoparticles. • The diamagnetic BaTiO₃ coating restricts magnetic ordering at the surface of the Ni core. • The structural transitions of BaTiO₃ observed on the magnetic properties of Ni@BaTiO₃ indirectly indicates the magnetoelectric coupling. • Exchange bias phenomenon is observed in the Ni@BaTiO₃ system. • The magnetoelectric coupling coefficient of 225 µV cm⁻¹ Oe⁻¹ is obtained. -- Abstract: Since core-shell structures are known to have a high surface area to volume ratio, they are preferred for next-generation memory device applications that require effective strain transfer at the ferroic interface. The present investigation reports the encapsulation of sea urchin-like Ni nanoparticles using BaTiO₃ nanoparticles to realize room temperature ME coupled Ni@BaTiO₃ system. The magnetic, electric and magnetoelectric properties of Ni nanoparticles partially coated with BaTiO₃ provide enough evidence for the existence of ME coupling between Ni and BaTiO₃ at their interface. Additionally, we have observed an exchange bias shift upon field cooling, which confirms the presence of the Ni-NiO-BaTiO₃ interface in the Ni@BaTiO₃ core-shell. The obtained magnetoelectric coupling coefficient of Ni@BaTiO₃ composite is 225 µV cm⁻¹ Oe⁻¹. The present study reveals that chemically derived sea urchin-like Ni@BaTiO₃ core-shell architecture can be a promising way to design strongly coupled multiferroic memory devices and sensors.