TY  - JOUR
A1  - Gati, Elena Aurelia
A1  - Tutsch, Ulrich
A1  - Naji, Ammar
A1  - Garst, Markus
A1  - Köhler, Sebastian
A1  - Schubert, Harald
A1  - Sasaki, Takahiko
A1  - Lang, Michael
T1  - Effects of disorder on the pressure-induced mott transition in κ-(BEDT-TTF)2Cu[N(CN)2]Cl
T2  - Crystals
N2  - 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 pc and the critical temperature Tc . 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. Our results demonstrate that the character of the Mott transition remains essentially unchanged at a low disorder level. However, after an irradiation time of 150 h, no clear signatures of a discontinuous metal-insulator transition could be revealed anymore. These results suggest that, above a certain disorder level, the metal-insulator transition becomes a smeared first-order transition with some residual hysteresis.
KW  - organic conductor
KW  - Mott transition
KW  - pressure
KW  - disorder
KW  - X-ray irradiation
Y1  - 2018
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/46369
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-463692
SN  - 2073-4352
N1  - This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
VL  - 8
IS  - 1, Art. 38
SP  - 1
EP  - 20
PB  - MDPI
CY  - Basel
ER  -