# Effects of Disorder on the Pressure-Induced Mott Transition in κ-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Cl

Gati, Elena; Tutsch, Ulrich; Naji, Ammar; Garst, Markus ; Köhler, Sebastian; Schubert, Harald; Sasaki, Takahiko; Lang, Michael

##### Abstract:
We present a study of the influence of disorder on the Mott metal-insulator transition for the organic charge-transfer salt κ-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Cl. To this end, disorder was introduced into the system in a controlled way by exposing the single crystals to X-ray irradiation. The crystals were then fine-tuned across the Mott transition by the application of continuously controllable He-gas pressure at low temperatures. Measurements of the thermal expansion and resistance show that the first-order character of the Mott transition prevails for low irradiation doses achieved by irradiation times up to 100 h. For these crystals with a moderate degree of disorder, we find a first-order transition line which ends in a second-order critical endpoint, akin to the pristine crystals. Compared to the latter, however, we observe a significant reduction of both, the critical pressure p$_{c}$ and the critical temperature T$_{c}$. This result is consistent with the theoretically-predicted formation of a soft Coulomb gap in the presence of strong correlations and small disorder. Furthermore, we demonstrate, similar to the observation for the pristine sample, that the Mott transition after 50 h of irradiation is accompanied by sizable lattice effects, the critical behavior of which can be well described by mean-field theory. ... mehr

 Zugehörige Institution(en) am KIT Institut für Theoretische Festkörperphysik (TFP) Publikationstyp Zeitschriftenaufsatz Publikationsjahr 2018 Sprache Englisch Identifikator ISSN: 2073-4352 KITopen-ID: 1000128905 Erschienen in Crystals Verlag MDPI Band 8 Heft 1 Seiten Art.-Nr.: 38 Vorab online veröffentlicht am 16.01.2018 Schlagwörter organic conductor; Mott transition; pressure; disorder; X-ray irradiation Nachgewiesen in DimensionsWeb of ScienceScopus
KIT – Die Forschungsuniversität in der Helmholtz-Gemeinschaft
KITopen Landing Page