23-12-2020  Wednesday

23Wed

Special lecture during online NIUS (Physics) camp on "Achieving Ultra-low Temperatures and Physics at those Temperatures"

Date: 23 December, 2020
Time: 18:00 - 19:00

Venue: Outside the Campus

Coordinator: Dr. Rajesh Khaparde / Prof. Anwesh Mazumdar

Speaker:

Professor S. Ramakrishnan (Director, TIFR, Mumbai)

Live on YouTube: https://youtu.be/AG85HF5EVok

Abstract:

It is important to study the physics of materials at ultra-low temperatures since small interactions responsible for many quantum phase transitions get wiped out even at normally possible low temperature (4K) of liquid helium. Often many new phenomena are discovered at low temperatures, which prompts the synthesis of new materials to show the same at higher temperatures leading to amazing applications. Therefore, it is of importance to study materials at ultra-low temperature.

This talk will describe the techniques to reach low and ultra-low temperatures and the investigation of phase transitions. The talk will describe the state of art nuclear refrigerator capable of cooling 5 Kg of Copper down to 0.000040 K built at TIFR. With this setup, superconductivity of Bismuth at 0.00053 K with a critical field of 0.000005 Tesla (one tenth of earth's magnetic field) has been discovered. This was a surprising discovery as superconductivity of Bismuth at ambient pressure has the lowest carrier density (one conduction electron shared by 100,000 atoms) and attracted international attention.