We present a large magnetodielectric (MD) effect of 65 % at 100 kHz with 5 T field in B-site ordered La2CoMnO6 (LCMO) polycrystalline sample. Frequency and temperature dependent impedance and dielectric studies under magnetic field divulge both intri
nsic and extrinsic origins for the observed MD effect. The temperature dependent Raman spectroscopy measurement has shown spin-lattice coupling that supports the intrinsic origin of the observed large MD response in LCMO. Extrinsic contributions to MD response mainly originate from disorder and interface effects; here, we signify this by hole carrier (Sr) doping at the A-site of the ordered LCMO sample. The comparison study has disclosed that with the disorder, the intrinsic polarization due to asymmetric hopping decreases significantly, and the disorder induced transport dominates in both MD and magnetoresistance behaviour with close resemblance.
We present sharp magnetization jumps and field induced irreversibility in magnetization in multiferroic Y2CoMnO6. Appearance of magnetic relaxation and field sweep rate dependence of magnetization jumps resemble the martensite like scenario and sugge
sts the coexistence of E*-type antiferromagnetic and ferromagnetic phases at low temperatures. In Y2CoMnO6, the critical field required for the sharp jump can be increased or decreased depening on the magnitude and direction of the cooling field; this is remarkably different from manganites or other metamagnetic materials where the critical field increases irrespective of the direction of the field cooling. The cooling field dependence on the sharp magnetization jumps has been described by considering exchange pinning mechanism at the interface, like in exchange bias model.
We have studied the magnetic field effect on low frequency dielectric properties of Pr0.6Ca0.4MnO3/polyvinylidene fluoride nanocomposite with 22.5% volume fraction of Pr0.6Ca0.4MnO3 nanoparticles. A strong magnetodielectric response was observed belo
w 120 K where Pr0.6Ca0.4MnO3 nanoparticles show the magnetic phase transition indicating a direct correlation between magnetism and dielectric properties. A large change of the dielectric permittivity ~ 30% has been observed in a magnetic field of 4.6 T with loss as low as 0.17 at 70 K. The observed magnetodielectric response has been attributed to the decrement of polaron activation barrier of Pr0.6Ca0.4MnO3 nanoparticles with the increase of magnetic field.
