Research Area

Our group is actively engaged in the experimental and theoretical study on various aspects of magnetism and superconductivity. For magnetism, the areas of interest include single crystal yttrium iron garnet, ferrites, permanent magnets such as Nd-Fe-B, materials displaying the phenomena of giant and colossal magnetoresistivity, and quantum simulation of complex materials. Meanwhile, we focus more on high Tc (e.g. YBCO and BSCCO) and low Tc materials (e.g. MgB2) for superconductors.

Research Areas:

Superconducting Materials

Superconductor is a material that has zero resistance when cooled below a critical temperature, Tc. For a superconducting material, it requires a cooling medium such as liquid helium or liquid nitrogen. Our research group focuses on producing materials such as YBCO, BSCCO, MgB2 and FeTe. Various methods were used to make superconducting materials such as solid-state, co-precipitation, sol-gel and thermal treatment methods.

Magnetic Materials

Colossal Magnetoresistance (CMR)

Manganites with the perovskite structure represent a very important family of oxides due to their extensive studied for colossal magnetoresistance (CMR) properties that can be potential used as magnetic sensing element. Generally, there are two category of CMR namely intrinsic and extrinsic MR. The intrinsic magnetoresistive properties, which govern the magnetic and transport properties of these materials, could be affect by altering their carrier concentration, average size of the interpolated cation, and mismatch effect on the Ln-site, B-site or Mn-site in hole doped manganites Ln0.7A0.3MnO3.

However, for extrinsic CMR (or also known as low field magnetoresistance, LFMR), it is highly affected by the intergrain transport between ferromagnetic (FM) particles. Since extrinsic CMR is a grain boundary controlled phenomena, magnetically dirty grain boundaries in the virgin state of the sample or grain reduction to nano-size help in achieving a better LFMR or increase the field sensitivity. Hence, nano-frabrication had become one of the research focus in the manganites work. Currently, our work is not only emphasized on bulk and nano-size compound synthesized via solid-state or wet-chemical method, thick and thin film fabriated via RF/DC Sputtering and Pulsed Laser Ablation system are also being actively investigated.

Giant Magnetoresistance (GMR)

The Giant Magnetoresistance (GMR) is the large change in the electrical resistance which is induced by applying an external magnetic field. Since the dicovery of GMR effect in 1988, GMR materials have great potential as the magnetic field sensing element due to its electric and magnetic properties can be varied in a very wide range, low power consumption, and small size. Hence, GMR had been utilized in many area such as magnetic field sensor, linear and rotary position sensor, data storage, head recording, nonvolatile magnetic random access memory, and biosensor.

GMR thin films composed of alternating ferromagnetic-nonmagnetic layers or nano-size of ferromagnetic granular embedded in the metal matrix. GMR material could be observed in several types of structures such as sandwich, spin valve (pinned sandwich), multilayer, and granular. Until now, researchers have still continued conduct research on GMR thin film, regarding on growth methods, constituent materials, as well as the variation of GMR structure or pattern. In our lab, GMR granular thin films fabricated via Pulsed Laser Ablation Deposition and RF/DC Sputtering Techniques are conducted and investigated.

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