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Shamashis Sengupta, du Tata Institute of Fundamental Research, Mumbai

Charge density wave phase transition in nanomechanical resonators

The charge density wave (CDW) phase transition involves a periodic
distortion of the lattice and the electron distribution in the crystal. The properties of charge density wave materials are significantly modified upon reducing the dimensions of the system. We have studied the change in elastic modulus in nanoscale crystals of CDW materials (NbSe2 and NbSe3). These experiments were done using the technique of heterodyne mixing in electromechanical resonators. The elastic moduli of these systems were seen to have an abrupt and large change ( 10%) at the phase transition. This is quite different from the results of earlier experiments on macroscopic crystals and highlights new aspects of the CDW transition at nanoscale.