Research

Topological Materials

Topological physics, an exploding area of research for its mystical behavior, is reshaping physics. Topology is the study of geometrical properties that are insensitive to smooth deformations as long as that deformation doesn’t involve tearing (stretching and clamping). Materials properties which are invariant under topological transformations property are known as topological materials, quantum Hall effect is the first realized topological phenomenon in condensed-matter physics. The physics of how electrons behave in topological materials, for instance, is analogous to what happens around black holes as they evaporate. In the past decade, People have found that topology provides unique insight into the physics of materials, such as how some insulators can sneakily conduct electricity along a single-atom layer on their surfaces. The mathematics hidden in materials keeps getting more exotic. Topological states of matter have shot from rare curiosity to one of the hottest fields in physics.Topological effects might be hiding inside perfectly ordinary materials, waiting to reveal bizarre new particles or bolster quantum computing. Our focus is to find such fantasy materials and understanding of basic physics.

Layered Materials

Layered materials have an interesting unique family of compounds which possess diverse applications in the field of optics, electronics, magnetism, energy storage and many more. The inherent nature of 2D properties in these layered materials add further significance to these classes of materials. The family of layered materials amalgamates a wide selection of elements which includes almost all the entries of the periodic table. Layered materials can be characterized as metals, semimetals, insulators and semiconductors with direct and indirect band gaps ranging from ultraviolet to infrared through the visible range. The wide spectrum of characteristics has shown them as potential candidates for the devices of nano-electronics, optoelectronics, thermoelectrics. Another interesting feature of layered materials is the possibility of structural engineering to be performed on it, which can extract the best out of these 2D materials, emerging out the cleaved layers with exotic properties. Hence layered materials provide us scope to perform comparative study on bulk to free standing monolayer/multilayer for device applications. Our main focus includes the prediction of such layered materials through our theoretical calculations and enable us to choose the best out of them.

Thermoelectric Materials

Recent advances in technology and industrialization together with a growing population prevail to search for new resources of energy which must be cost effective and environmentally friendly. Thermoelectricity is the one among the modern era of technology, which gathered enormous attention from researchers and scientists in materials science. The major advantage of this technology is the conversion of lost heat into another form of energy such as electrical energy. A few chalcogenides and pnictides were found to be good thermoelectric materials. Our aim is to study the various kinds of materials like inorganic, oxychalcogenides, transition metal di-chalcogenides, organic and layered materials etc. for their peculiar thermoelectric applications using first principles. The first principle methods help us to predict the electronic and thermoelectric properties before performing actual experiments to extract the real applications, and gives us an idea of selecting a proper combination of elements with avoiding wastages. Till date, our group has worked on various materials like transition metal di-chalcogenides like ReS₂ and OsX₂(X=S, Se and Te) including other chalcogenides SrAgChF(Ch = S, Se and Te) and Organic perovskite CH3NH3SnI₃, and predicted that these materials have future scope in thermoelectrics. Our future goal incluedes the prediction of material with low lattice thermal conductivity using three phonon processes and its thermoelectric properties.

Magnetic Materials

Magnetic materials are always the primary choice for any researcher because of their utility and exotic applications in all domains. Computers and other accessories like memory devices and discs have been in use since ages. The process of high speed computation and digitalization restricts the wastage and cost of production of real materials. Earlier, the memory devices were made of materials with only one degree of freedom ‘i.e the charge of an electron’ in order to transfer the data. These are replaced by magnetic materials which effectively use the spin of an electron additionally. Spintronic materials serve the purpose. The advantage of spintronic devices is that the spin current can be transmitted with less power consumption. MRAMs and Hard Disk Drives are effectively using the spin of electrons. Thus the utilisation of spin properties of an electron can drastically change the whole world and the research is progressing both in experimental and computational field with the aim of searching new spintronic devices.

High Pressure studies

Pressure plays a dramatic role in our daily lives. It is a basic thermodynamic parameter which can drastically influence the properties of materials. The effect is more pronounced in solids and several exotic properties which are not found in ambient conditions can be obtained under pressure. For example, carbon is used for a variety of applications. It is used as a graphite in pencil and in other house related stuff. But it transforms into the diamond hardest substance under high pressure. Likewise, sulfur can be an electrical conductor at high pressure. Single bonded cubic form of nitrogen which is an allotropic form of nitrogen can be obtained at high pressure above 110 GPa and temperature above 2000 K. The obtained single bonded nitrogen has unique properties such as energy capacity which is five times larger than the most powerful energetic materials. Pressure/strain/chemical pressure can play a vital role in tuning the physical properties such as topological properties, superconducting properties, and electronic structure properties. By using the pressure, we can develop new high energy efficient materials. There are many interesting features of the pressure. This kind of application inspired us to choose the pressure study on the materials.

Electronic Topological transition (ETT)

Electronic Topological transition (ETT), an isostructural transition occurs without any volume discontinuity, and the Wyckoff positions of atoms are not modified during transition. It occurs under high pressure due to change in Fermi-surface topology. Numerous studies are available, reporting the insulator to metal transition or vice-versa under high pressure and lead to different applications than that of in the ambient case. A few of the studies on magnetic materials reported the change in magnetic moments under the electronic topological transition. In antiferromagnetic Zr2TiAl, three ETTs at V/V0 of 0.96, 0.92 and 0.85 have been observed which lead to the drop in the magnetic moment of Ti atom under compression. High entropy quaternary Heusler alloys CuNiMnAl and CuNiMnSn are found to be ferromagnetic, and display the ETT along with change in magnetic moment under high pressure. Such systems are interesting and we focus on exploring the materials which shows the Electronic Topological transition under external conditions with the aim of achieving 100% spin polarization in magnetic materials.