Dielectric critical behaviour at a metal-insulator transition under lattice compression |
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Authors: | Shailesh Shukla Nitya Nath Shukla |
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Affiliation: | a School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067, India b Department of Physics, Indian Institute of Technology, Kanpur 208016, India |
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Abstract: | We study dielectric critical behaviour around a continuous metal-insulator transition in crystalline Cesium Iodide induced by changing the lattice parameter. The ab initio calculations of band structure and various quantities related to the dielectric response are performed in the transition region, within the local density approximation of the density functional theory. These calculations allow us to establish the power-law singularities of various quantities on two sides of the transition. The exponents obtained here are mean-field like due to the approximation in which interactions and disorder are treated. The critical behaviour is discussed by applying the scaling principle to the wavevector and frequency dependent dielectric function. We further investigate the effect of dielectric anomalies on optical properties by calculating the reflectance around transition region taking the ionic contribution to the dielectric function also into account. We find that the reflectance as a function of frequency shows very different kind of behaviour on both sides of the metal-insulator transition. |
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Keywords: | 71.30.+h 71.20.Mq 71.20.Nr |
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