Research and Research Tools

TOPICS INCLUDE:
Magnetoelectric Multiferroics (ME MFs):
Magnetoelectric multiferroic materials, which simultaneously have some form of magnetic and ferroelectric order parameters have potential for multifunctional device applications. Such materials show promising coupling, known as magnetoelectric (ME) effect, between magnetic and electric order parameters.The direct ME coupling present in a single-phase material, such as Cr2O3, BiFeO3, TbMnO3. Whereas the indirect ME  effect, which may be observed via strain in composite materials, where the magnetic (magnetostrictive materials, such as CoFe2O4, LaSrMnO3) and electrical (piezoelectric materials, such as BaTiO3, PbZrxTi1-xO3) order parameters arise in separate but intimately connected phases.

  • We are interested in synthesis and characterization of both single phase and biphasic (nanocomposite) magnetoelectric multiferroic films and bulk powders. TbMnO3, PZT:CFO, HoCrO3, DyCrO3 are some of the recent systems that we have studied.

Manganite Films with Colossal Magnetoresistance Properties:

Rare-earth manganite (RMnO3) materials with perovskite structure have been of intense research in last decade because of their inherent potential to exhibit many interesting properties including colosal magnetoresistance (CMR), charge-ordering, (CO), etc. Hole-doped manganites show magnetoresistance (MR) phenomena, which is the gigantic decrease of resistance by application of a magnetic field. Such a gigantic negative MR (CMR) is of great interest for many applications. In single crystal or epitaxial films, the maximum value of negative MR is observed near the Curie temperature (Tc), which is their intrinsic property. Interest in the MR of these manganites has revived due to even more astonishing magnetic field induced insulator−metal and/or lattice-structural transitions.
Highly sensitive and electrically readable magnetic-field sensors have been in industrial demand for the read-head of magnetic memories and the CMR oxides may be one such candidate material.

  • We are interested in examining the effect of strain (when fabricated in thin film form), processing conditions, and divalent doping (at the rare-earth site) on the magnetic, magnetotransport, and magnetocaloric properties of these materials.

Manganite:Insulator Composite Films with “Low-Field Magnetoresistance” for Magnetic Field Sensors:
Hole-doped perovskite RMnO3 systems show extrinsic MR bahavior due to grain, boundaries, artificial grain boundaries, atomic size defects in the film-substrate interface, nano-size inclusions (that appear during film processing), or when prepared as nanocomposite with insulator materials.

  • We are interested in the synthesizing and understanding the magnetotransport behavior in (i) manganite films in different processing conditions that show grain boundary effect, (ii) heterostructured films, and (iii) nanocomposite manganite films.

Magnetic Ferrite Nanoparticles
Nanoparticles (NPs) of ferrites, such as Fe3O4 and CoFe2O4 (CFO) have a wide range of applications. Due to their tunable magnetic properties and small size magnetic NPs have a great potential for implementation in the fields of high-density data storage, MRI contrast agents, targeted drug delivery, hyperthermia treatments, chemical catalysis and magnetoelectric composite films.
The size of NPs affects their magnetic properties. For NPs below this critical size, the Hc rapidly decreases with size until particles display superparamagnetic (SPM) behavior (Hc = 0). In the SPM state, the particles are small enough to have only a single magnetic domain.

  • We are interested in understanding the detailed magnetic properties of magnetic properties and their use in various applications.

Ferroelectric Thin Films for Microwave Devices for FRAM: (Ba/Sr)TiO3, PZT, etc are prepared via sol-gel method

RESEARCH TOOLS AVAILABLE in the group:

Spin coater (in fume hood), Glove box, furnaces, LCR meter (Agilent E4980A), IV measurement using Keithley meter (Keithley 6487), ferroelectric tester (RT66B), etc.

 

 

 

Physical property measurement system with these options:

  • Resistivity measurements (ac and dc) from 5-400 K with or without dc magnetic fields of upto 9 Tesla.
  • magnetic measurements using vibrating sample magnetometer upto 9 T (1.9 K-400K): {powder, nanoparticle, nanowires, composites etc}
  • AC susceptibility measurement (up to 17 Oe and 10-10 k Hz, 1.9 K-350 K),