Showing papers by "Mahesh Kumar published in 1999"
TL;DR: In this paper, a non-linear signal was observed for antiferromagnetic materials and the shift from linearity was attributed to the tilt in the octahedra of octahedral structures.
Abstract: and are members of the Aurivillius family of compounds having simultaneous electrical and magnetic ordering. Magnetoelectric measurements carried out in a linear time-varying magnetic field with an alternating-current field superimposed yielded a non-linear signal. The shift from linearity, which is not usually observed for antiferromagnetic materials, may be due the tilt in the octahedra. The variation of the magnetoelectric output with temperature for and indicated magnetic anomalies with enhanced sensitivity, corresponding to those in magnetization data.
146 citations
TL;DR: In this paper, magnetoelectric measurements carried out with a superimposed alternating-current magnetic field, together with a time-varying direct current magnetic field in isothermal conditions, indicated nonlinearity.
Abstract: BiFeO3 forms solid solutions with BaTiO3, over the entire compositional range, with different crystal symmetries. Magnetoelectric (ME) measurements carried out with a superimposed alternating-current magnetic field, together with a time-varying direct-current magnetic field in isothermal conditions, indicated non-linearity. The peak observed coincided with a metamagnetic transition in the magnetization data. Rather than the spin flop reported earlier, it is a gradual reorientation of spins towards the field direction that destroys the spiral spin arrangement. With increasing content of BaTiO3, a quadratic signal was observed, indicating the structural dependence of the magnetoelectric effect. The temperature variation of the ME output in the investigation carried out for x = 0.75 indicates magnetic transitions.
61 citations
TL;DR: BaTiO3, when doped with minute concentrations of Bi+3 and Fe+3, was found to exhibit relaxor behavior as mentioned in this paper, and the results have been discussed using impedance and modulus spectroscopy.
Abstract: BaTiO3, when doped with minute concentrations of Bi+3 and Fe+3, was found to exhibit relaxor behavior. The data on dielectric constant performed as a function of frequency and temperature indicate a reduction in the transition temperature with increase in frequency. A poled sample indicated a decrease in the transition temperature compared to an unpoled sample. It was found that the grain boundary capacitance were negligible and the relaxations occurred are only due to the bulk of the sample. The results have been discussed using impedance and modulus spectroscopy.
12 citations