Exploring the room temperature multiferroic behavior and negative exchange bias effect in Ho0.05Y0.95Fe0.90Ti0.10O3 nanoceramic

The persistent pursuit of multiferroic materials exhibiting ferroelectric and ferromagnetic properties at typical room temperature conditions is primarily driven by the anticipation of groundbreaking advancements in device technology. This paper presents a detailed investigation of the structural, dielectric, magnetic, and ferroelectric properties of sol-gel synthesized Ho _0.05Y _0.95Fe _0.90Ti _0.10O ₃ (HYFTO) nanoceramic. Rietveld analysis of neutron diffraction data reveals microstructural parameters, such as bond angle and bond length, providing valuable insights. The Williamson-Hall (W-H) plot yields an average crystallite size of 35.72 nm and a strain of 6.18×10 ⁻³ . Magnetisation vs Temperature (MT) and Magnetisation vs Magnetic field (MH) measurements are carried out over a wide temperature range of 900 K – 3 K. Neutron diffraction measurements and their analyses confirmed the existence of ferromagnetic ordering where maximum magnetization is ∼1.1 µB which is approximately 11 times greater than that of YFeO ₃ (YFO) ∼0.1 µB, attributing to higher spin canting. Interestingly, doping impedes the transition temperature (T _N ) to 646 K for HYFTO. The increase in the ferromagnetic component observed below 10 K, as determined from the fitting of the MH loop, corresponds to the transition of Ho to its ferromagnetic state. Field dependent magnetization reveals significant horizontal shifts in the Field cooled (FC) hysteresis loops compared to the symmetric Zero-field cooled (ZFC) loop, indicating an negative exchange bias (EB) effect and an exchange field of ∼500 Oe at 300 K. The co-doped sample exhibits a high dielectric constant, accompanied by a remarkably low tangent loss of 0.56 at room temperature. The sample demonstrates a transition from paraelectric to ferroelectric state at approximately 420 K, highlighting its potential as a type II multiferroic material suitable for room temperature applications. Co-doping enhances the ferroelectric properties, enabling the sample to withstand higher electric fields with increased saturation polarization (∼0.31 µC/cm ² ) and coercive field (∼8.96 kV/cm). Lower leakage loss observed in HYFTO, as indicated by its JE characteristics, further confirms its superior ferroelectric nature. In addition, the magnetoelectric coupling is enhanced by ∼3.6 times compared to bare YFO. These significant advancements in magnetic properties, electric field tolerance, and magnetoelectric coupling highlight the potential of this study and its promising applications in device technology.