You are here

Exploring Physics at the Nanoscale

We all know the story of how computers evolved from mammoth sized calculating machines to miniaturized, user friendly, ubiquitous devices used for anything and everything. Devices of progressively decreasing size and ever increasing capabilities are a necessity of the modern age and are made possible by understanding and taking advantage of the properties of various materials around us in all their different sizes and phases. This is why material science reigns as a field of much research interest and activity.

An up and coming laboratory in this scientific discipline from India is the Mesoscopic Physics Group headed by Dr. Aveek Bid at the Indian Institute of Science, Bangalore. Dr. Bid’s group deals with mesoscopic objects – those in the size range of nanometers to micrometers i.e. the size of individual molecules to one fiftieth the diameter of human hair. These objects, by virtue of being governed by the laws of quantum mechanics, exhibit properties distinct from their macroscopic counterparts. The applied science of mesoscopic physics aims to exploit and manipulate these properties to build nanodevices.

Established in December 2010, the lab has grown to produce significant research output in a short span of time. Dr. Bid’s research interests span a wide range of materials. He has worked on electrical conductance properties of low dimensional systems like metal wires of nanometer thickness and quantum dots - tiny crystals of semiconducting material with diameter in the nanometer range, and fractional quantum hall effect. His group at IISc conducts research on electronic transport in various mesoscopic systems. Materials like graphene and two-dimensional electron gas found at the interface between two oxides are being studied.

The lab is equipped with one of the best low temperature research facilities in the world – has a fridge capable of cooling down the samples to as low a temperature as 10 mK (close to the theoretical minimum temp of -2730C) in the presence of a very high magnetic field of 16 T. It is being used to study single atomic layer thick samples of superconductors and other semiconducting materials.

Recently, the group made news for discovering a novel type of transient superconductivity at the interface between two metal oxides, in response to an applied external magnetic field.  Ferromagnetism is the phenomenon of alignment of electronic spins inside a material in the direction of the external magnetic field. Superconductivity refers to the presence of zero electrical resistance in some materials when they are cooled down to a certain temperature. Ferromagnetism and superconductivity are generally termed as antagonistic properties. However, the team found that the metal oxide interface, in fact, exhibits a coexistence of these properties as well as their controlled tunability using external magnetic field, putting forward tremendous potential in device applications.

The recent focus of Dr. Bid’s research has been on graphene, a form of carbon consisting of 2-D planar sheets which are one atom thick.Apart from trying to understand the underlying physics behind the properties exhibited by graphene, the group’s research is also oriented towards practical applications, especially sensing. The group has discovered a new sensing mechanism using graphene which is enormously faster and more efficient than the existing ones.

 “A very important requirement of modern age from science and technology is smart sensors and amongst different types of sensors, gas sensors are probably the most important”, says Dr. Bid. A reliable gas sensor is necessary for numerous applications from pollution control to safety and security purposes like detecting gas leaks in industries and mines, explosive detection etc.

Graphene being a two dimensional material, all of its volume is exposed to the surrounding. The adsorption or desorption of gas molecules on the surface changes graphene’s electrical conductance which is measured in the conventional sensing method.Dr. Bid’s group has developed a novel technique to monitor the intrinsic electronic noise of a graphene field effect transistor in real-time and do sensing using the observed change in noise magnitude. In addition to a small response time and an order of magnitude better sensitivity, the presence of different chemical species in the ambient can be figured out from the acquired data as well.

Dr. Aveek’s lab has ambitious plans lined up for the future. “We are planning to add various capabilities like in-situ sample preparation to have some of the cleanest material in the world” says Dr. Bid. With cutting edge research facilities and good research output, the mesoscopic physics laboratory has demonstrated the potential to grow as one of the pioneering materials research centres of India.


About the scientist:

Dr. Aveek Bid is currently an assistant professor at the Department of Physics, Indian Institute of Science, Bangalore.