Optical Probe of Carrier Doping by X-Ray Irradiation in the Organic Dimer Mott Insulatorκ−(BEDT−TTF)2Cu[N(CN)2]Cl

T. Sasaki, N. Yoneyama, Y. Nakamura, N. Kobayashi, Y. Ikemoto, T. Moriwaki, H. Kimura
2008 Physical Review Letters  
We investigated the infrared optical spectra of an organic dimer Mott insulator κ-(BEDT-TTF)_2Cu[N(CN)_2]Cl, which was irradiated with X-rays. We observed that the irradiation caused a large spectral weight transfer from the mid-infrared region, where interband transitions in the dimer and Mott-Hubbard bands take place, to a Drude part in a low-energy region; this caused the Mott gap to collapse. The increase of the Drude part indicates a carrier doping into the Mott insulator due to
more » ... defects. The strong redistribution of the spectral weight demonstrates that the organic Mott insulator is very close to the phase border of the bandwidth-controlled Mott transition.
doi:10.1103/physrevlett.101.206403 pmid:19113361 fatcat:n7eacp4uqrf4bcvlez4a4ldcau