Research Projects

Hybrid organic inorganic halide perovskite (HOIP) is one of the important family of materials that exhibit spin orbit coupling (SOC) due to the heavy elements like lead. This SOC along with broken inversion symmetry results in ferroelectricity and quantum phenomena like Rashba splitting which are very important for spintronic devices. The materials having both ferroelectric polarization and Rashba splitting property are called Rashba ferroelectric material. In such material SOC depends on electrical polarization which is essential for spintronic application. Although SOC is present in HOIP, it does not always show broken inversion symmetry due to its centrosymmetric structure. Strain engineering is a promising way to break the inversion symmetry or to induce chirality inside the molecule. Strain can result in structural change by altering the bond length and bond angle. Strain can be introduced externally or internally. External strain can be induced by applying mechanical stress, annealing or cooling the deposited HOIP film etc. Chemical modification through doping or substituting appropriate elements in A, B or X site of ABX₃ HOIP as well as transformation of 3-dimensional to 2-dimensional structure can also generate lattice strain in the material. Here, we will focus on generating strain through chemical modification in hybrid lead halide perovskite and demonstrating the extent of Rashba splitting and ferroelectricity. Initially we will synthesize 3-D Methylammonium lead iodide and methylammonium lead Iodide chloride with the variation of chloride content. The variation of chlorine content can modulate the lattice strain in the perovskite structure. Different characterization techniques like TEM, HRTEM, XRD will be used to confirm the structural property of the synthesized samples. To understand the chirality, circular dichroism measurements will be performed. To further understand the SOC, magnetic circular dichroism technique can be employed. This method gives us an overview of magnetic field and symmetry broken effect on Zeeman splitting. Higher Zeeman splitting indicates higher SOC which is an important requirement for spintronic device. Polarization dependent photoluminescence spectroscopy also can help to understand the extent of Rashba effect. Piezoelectric force microscopy will be employed to study the ferroelectric effect. we will explore the effect of strain in the Rashba splitting and ferroelectricity in two-dimensional hybrid halide perovskite. By introducing large A site cation i.e. C₄H₉NH3+(Butylammonium) in place of small cations like methylammonium can induce lattice strain in 2-D halide perovskite structure. Here, we will introduce a large cation in the A site of methylamine lead iodide chloride. This work will give an comprehensive idea of the relation between strain and chirality to enhance the ferroelectric polarization and Rashba splitting.