Single Crystal Growth of Constantan by Vertical Bridgman Method

This project deals with aspects involved in the growth of single-crystals of Constantan. Constantan is an alloy of Nickel in Copper, whose technological interest is that resistance is independent of temperature over a very large range of temperatures (hence the name Constantan). This, along with other suitable properties such as high strain sensitivity, high resistivity and low coefficient of thermal expansion makes it the principal component of all modern strain gauges used. However, Constantan also represents exactly the critical composition of Nickel in Copper (45% by weight Ni in Cu), which is the border between ferromagnetism and paramagnetism at low temperature. Such a transition in magnetic states at low (zero) temperature is called a quantum phase transition, and results in a uniquely scaling excitation spectrum. The eventual purpose of growing these single crystals is to validate our hypothesis that in fact the technologically relevant properties of Constantan are the result of quantum critical fluctuations. This can be investigated by a technique called inelastic neutron scattering.