Magnetic and magnetoelectric studies in pure and cation doped

Abstract

We report the effect of divalent cation (A) substitution on magnetic and magnetoelectric properties in Bi 1-x A x FeO 3 (A= Sr, Ba and Sr 0.5 Ba 0.5 ; x = 0 and 0.3). The rapid increase of magnetization below 100 K and a peak at the Neel temperature T N = 642±2 K found in BiFeO 3 is suppressed in the co-doped sample (A = Sr 0.15 Ba 0.15 ). All the divalent cation doped samples show enhanced magnetization with a well defined hysteresis loop compared to the parent compound. Both longitudinal (L-α ME ) and transverse (T-α ME ) magnetoelectric coefficients with dc magnetic field parallel and perpendicular to the direction of induced voltage, respectively, were measured using dynamic lock-in technique. It is found that the T-α ME increases in magnitude and exceeds the L-α ME with increasing size of the A cation. The maximum T-α ME = 2.1 mV/cmOe in the series is found for A = Sr 0.15 Ba 0.15 , though it is not the compound with the highest saturation magnetization. The observed changes in the magnetoelectric coefficient are suggested to possible modification in the domain structure and magnetoelectric coupling in these compounds.1

The magnetic properties of BiFeO3 and Bi(Fe0.95Zn0.05)O3

“…With temperature decreasing from room temperature, for both FC and ZFC curves, magnetization continues to decrease, confirming the antiferromagnetic exchange interaction of spins. The fast increase of magnetization with decreasing temperature below 25 K was also observed recently, which was attributed to the development of incommensurate sinusoidal spin structure in BiFeO 3 [12]. However, the slow decrease of magnetization with decreasing temperature from 300 to 250 K followed by the fast decrease of magnetization is different with the antiferromagnetic BiFeO 3 which shows almost linear temperature dependence below T N [12], indicating the slight different spin arrangement in our BiFeO 3 ceramic.…”

“…The fast increase of magnetization with decreasing temperature below 25 K was also observed recently, which was attributed to the development of incommensurate sinusoidal spin structure in BiFeO 3 [12]. However, the slow decrease of magnetization with decreasing temperature from 300 to 250 K followed by the fast decrease of magnetization is different with the antiferromagnetic BiFeO 3 which shows almost linear temperature dependence below T N [12], indicating the slight different spin arrangement in our BiFeO 3 ceramic. The magnetization value of FC curve measured under same magnetic field was always higher than that of ZFC curve, confirming the weak ferromagnetic properties.…”

“…And it can be seen that by doping of 5% Zn, the intensity of the Bi 12 (Bi 0.5 Fe 0.5 )O 19.5 peaks increases, indicating that more impurity phase formed. Except for Bi 12 [10]. Fig.…”

Dielectric anomalies due to grain boundary conduction in chemically substituted BiFeO3

“…After a certain value of magnetic fields, the magnetostriction gets saturated producing a nearly constant electric field, thereby decreasing magnetoelectric coefficient (a) with further increasing the magnetic field. 90 Arya et al 42 42,91,92 Magnetoelectric (ME) coupling in single-phase ceramics originates due to spin-orbit coupling along the preferential axis of spins; however, significant change in the strength of anisotropy and local symmetry due to external electric/magnetic field decides the magnitude and direction of magnetoelectric coefficient as a function of electric/magnetic fields. Restricting ourselves to the linear coupling term, then, E MEðHÞ ¼ aH where E is applied electric field, H is applied magnetic field and a is ME coefficient.…”

The magnetic properties of La doped and codoped BiFeO3

“…were used to partially substitute Bi, and Co, Ni, etc. were used to partially substitute Fe, which significantly enhanced the room temperature ferromagnetism [9][10][11]. * Corresponding author.…”