Self-biased characteristics of NZCF/BCZT layered magnetoelectric composites: A novel coupling paradigm in magnetoelectricity

Here, we investigate room temperature magnetoelectric (ME) behavior of ferroelectric Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) and ferrimagnetic Ni0.75Zn0.20Co0.05Fe2O4 (NZCF) layered composites. The ferroelectric ceramics (thickness, t, ~ 0.6, 0.8, and 1.0 mm) are stacked at magnetic specimen of fixed t ~ 1 mm, coupled with conducting silver epoxy. The phase formation, surface morphology, dielectric, magnetic, magnetoelectric and magnetodielectric characteristics of bilayer composites have been studied in the present work. The maximum value of magnetoelectric (ME) coupling coefficient (alpha ME) is found to be 70, 90, and 110 mVcm(-1)Oe(-1) for composite having ferroelectric layer thickness t ~ 1, 0.8, and 0.6 mm, respectively. More importantly, alpha ME(H & RARR;0) remains finite for composite (t ~ 0.8, and 0.6 mm) in zero magnetic field, which is a clear evidence of self-biasing phenomenon in NZCF/BCZT layered composite. For closer insight about underlying mechanism, we estimate magnetodielectric (MD) coefficient for the layered composite. The MD coefficient is found to be significantly high ~6.32% for the thickness 0.6 mm. MD% vs magnetic field, H, curves exhibit steeper field dependence in low field region and for H >= 2 kOe MD possess saturation characteristics. The high saturation characteristics suggest that the magnetoelectricity in layered composite is driven by magnetostriction mechanism and causes robust ME coupling. Further, we obtain electrical signal ~143 mV with the Hdc ~250 Oe, as a consequence of interplaying nature of magneto(striction)-piezo(electricity). Such a sizeable response will improve the underlying intimacy between technology and practical application. The study reveals that the pellet based layered composites may be a proven strategy for the realization of self-biased ME devices.

Automated summary

In this study, the magnetoelectric behavior of ferroelectric and ferrimagnetic layered composites was investigated. The self-biasing phenomenon and magnetodielectric characteristics were observed. The robust magnetoelectric coupling in the layered composite is driven by the magnetostriction mechanism. The study suggests that pellet based layered composites could be an effective strategy for self-biased magnetoelectric devices.