Condensed Matter Physics
What is Condensed Matter Physics?
Condensed matter is a branch of physics where we study about the condensed or solid state (as opposed to gaseous states) of matter. We are surrounded by various matter. They exist broadly in three different forms; gaseous, solid, and liquid. In case of gaseous matter, the molecules are sparsely distributed. The forces between them are not strong enough to hold them together. In case of liquid and solid matter, the density of molecules are higher. The forces among the molecules is strong enough to hold them together. Condensed matter physics deals with such states of matter where the attraction among the molecule is strong. Here, we will specifically focus on the solid forms of matter. In few cases, we will discuss liquid phases as well, when we will learn about the liquid crystals (we all heard about the LCD or liquid crystal display used in mobile phones, laptops, and TV screens).
Unlike in gaseous or liquid states, the constituent atoms/molecules in solid state are ordered, they do not move randomly. However, the atoms have thermal vibration with respect to their equilibrium position inside the solid. When we have a large number of atoms or molecules (of the order of 1023 molecules per cm3) together and the interaction or attraction among them is very strong, they bond together. Often the atoms (or group of atoms) arrange themselves in a repeated configuration and form crystal structure.
Why study condensed matter?
The world around us is made up of materials. Some are useful. We need to understand them in order to use them for specific applications. For example, copper wire is used for electrical conduction. Silicon is used as transistors in our computers including mobile phones. Liquid crystals are used in digital display, and so on.
Are we interested in finding the material for next generation of electronics? Then we need to study condensed matter physics. We need to understand the structure of the material. We need to understand their electronic, mechanical and thermal properties.