V.R. Palkar

Multifunctional behavior of ZnO supported Bi1−xDyxFeO3 nanorods

We have shown that it is possible to realize multifunctional Bi1−xDyxFeO3 (BDFO) nanorods by coating BDFO film on ZnO nanorods. These BDFO coated ZnO (BDFO/ZnO) nanorods are obtained by depositing BDFO on vertical ZnO nanorods grown on Si substrate by using pulsed laser deposition technique. The BDFO/ZnO rods exhibit coexistence of ferroelectric and ferromagnetic properties with significant coupling between two order parameters at room temperature. Moreover, the piezoresponse of these nanorods is found to be even superior to pure ZnO nanorods. The unique multifunctional behavior of these nanorods at room temperature could find different applications in nanodevices like sensors, power generators, etc. with ease and flexibility in operation.

Study of multiferroic Bi0.7Dy0.3FeO3 based tunable ring inductor

Bi0.7Dy0.3FeO3 (BDFO) exhibiting multiferroicity at room temperature is used as a core material for the first time to fabricate a ring-type inductor. More importantly due to the presence magnetoelectric coupling, the BDFO inductor could be tuned magnetically as well as electrically. It is observed that tunability of this inductor is better in the presence of magnetic field than electrical field. This behaviour is correlated to high electrical loss factor (tan δ) of the core material. The dissipation of electrical energy perhaps impedes the strain induced change in permeability. However, there are chances of improvement if tan δ of BDFO is controlled. Nevertheless, simplicity in fabrication and flexibility in operation make tunable BDFO inductors attractive for novel applications. The results give confidence to work on development of miniaturization of BDFO inductor.

Characterization of Au/PbTi0.5Fe0.5O3/Si structure for possible multiferroic based non-volatile memory applications

Magnetoelectric multiferroic PbTi0.5Fe0.5O3 films are deposited on a ⟨100⟩ conducting p-Si substrate without any buffer layer by using pulsed laser deposition and characterized for possible non-volatile memory applications. Their crystalline structure and surface morphology were characterized by using x-ray diffraction and AFM techniques. HRTEM was employed to determine the film–substrate interface. The electronic structure of the film was investigated by XPS, and no signature of metal was found for all the elements. The chemical shift of the Ti 2p XPS peak is attributed to the replacement of Ti with Fe in the PbTiO3 matrix. Piezoelectric force microscopy (PFM) results indicate the 180° phase shift of ferroelectric polarization. The upward self-polarization phenomenon is also observed in the PFM study. Magnetic and magneto-electric coupling measurements were carried out to confirm the magnetic nature and electro-magnetic coupling characteristics. C–V measurements exhibit clock-wise hysteresis loops with a...

Observation of thickness dependent properties in novel multiferroic thin films

Multiferroics exhibit simultaneous coexistence of electric and magnetic ordering with coupling between two order parameters. These materials therefore find novel applications like multiple memories apart from MEMS sensors and actuators etc. Here we report the thickness dependent multiferroic properties of Bi0.7Dy0.3FeO3 films grown on Pt/TiO2/SiO2/Si substrate by pulsed laser deposition technique. In these films, magnetic anisotropy is developed non-linearly with the thickness. It is correlated to stress developed during growth process due lattice mismatch, difference in thermal coefficient, internal defects etc. The lattice cell parameter c also changes arbitrarily with the thickness of the film but correlates with stress. The saturation polarization (Ps) values scale with c parameter. The information obtained by this study would be significantly useful in innovative devices planned with this advanced material.

In-plane anisotropy in La0.7Sr0.3MnO3 (LSMO) patterned thin film

We report an anisotropy in the resistivity with in-plane applied magnetic field for patterned thin film of LSMO(32 nm) on STO (001) substrate with aspect ratio of 20. Anisotropy in the electrical resistivity ρAMR∼0.51% is observed at room temperature. Decrease in the resistivity, when applied current and magnetic field are perpendicular to each-other, is due availability of small cross-sectional area for scattering. In this experiment, we have measured these values at 300 K, 200 K, 100 K and 10 K, with 5 kOe in-plane magnetic field and observed that AMR decrease with decrease in the temperature due to availability of lesser thermal energy.

Growth Of Multiferroic Rods Using Si Template And Study Of Their Magnetic Properties

We have been successful in developing Bi0.7Dy0.3FeO3 (BDFO) material which exhibits the multiferroic behavior at room temperature with significant coupling in bulk as well as thin films. If this material could be fashioned as nanorod, implementation in devices could be more straight forward. We have therefore used vertically aligned arrays of silicon rods (∼5 μm in length and ∼0.5 μm in diameter) as template to direct the growth of a uniform layer of the BDFO on the surface of the Si rods by using pulse laser deposition technique. XRD results indicate presence of phase pure BDFO layer on Si. Magnetic properties of BDFO/Si rods were studied by using VSM. M‐H curve indicates the ferromagnetic behaviour of the rods at room temperature. Magnetic force microscopy (MFM) was used to study the magnetic domain structure of the individual BDFO/Si rod.

Processing and Switching Behavior of Multiferroic (Bi0.7Dy0.3FeO3) Microstructure Arrays

Multiferroic systems, which exhibit coexistence of both ferroelectric and ferromagnetic ordering at room temperature, are of great importance for a variety of device applications. Due to coupling between the two order parameters, it is possible to bring polarization in the multiferroic systems by either means (applying electric or magnetic field). We have been successful in developing material (Bi0.7Dy0.3FeO3) which exhibits the multiferroic behavior at room temperature with significant coupling in bulk as well as thin films. We therefore propose to develop a procedure to fabricate multiple memory devices using this new compound.

Fabrication and characterization of novel multiferroic cantilevers for microtransuducers

It is believed that new technologies tend to initiate with new materials and manufacturing processes, which are used for new products. Magnetoelectric multiferroics are the class of materials which have coexistence of magnetic and ferroelectric properties, with coupling between two order parameters. These materials therefore find novel applications in multiple memories apart from MEMS sensors and actuators. However, the research on these materials is not reached to technology level. The microfabrication technologies required for preparing device structures of these materials need extensive optimization. Patterning these films into the required structures can also be a challenge. This paper presents the first achievement towards the practical realization of MEMS devices of such novel promising material.