Dresden 2017 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 30: Transport: Molecular Electronics and Photonics (jointly with CPP, HL, MA, O)

CPP 30.10: Talk

Wednesday, March 22, 2017, 12:00–12:15, HSZ 201

Charge Carrier Dynamics in κ-(BEDT-TTF)₂Cu[N(CN)₂]Cl: From Mott Insulator to Quantum Spin Liquid — •Jana-Isabelle Polzin¹, Benedikt Hartmann¹, Takahiko Sasaki², and Jens Müller¹ — ¹Institute of Physics, Goethe University Frankfurt, Germany — ²Institute for Materials Research, Tohoku University, Sendai, Japan

The organic charge transfer salts κ-(ET)₂X are model systems for studying strongly-correlated charge carriers and the Mott metal-insulator transition in reduced dimensions. Recently, the influence of quenched disorder attracted considerable attention. Conducting layers of ET molecules are separated by thin, insulating sheets with anions X, resulting in a quasi-2D electronic band structure. Within the ET layers the molecules are arranged in dimers forming a triangular lattice. One free charge carrier exists per dimer, its spin being geometrically frustrated. The Mott insulator κ-(ET)₂Cu[N(CN)₂]Cl shows antiferromagnetic ordering at T_N≈27 K. It has been shown that increasing disorder induced by X-ray irradiation drives the Mott insulating state with long-ranged antiferromagnetic order into a quantum spin liquid state [1]. Here, we discuss comparative measurements of fluctuation spectroscopy on pristine and irradiated samples in order to investigate the changes in electronic transport mechanism and low-frequency charge carrier dynamics [2] when tuning the Mott insulator to the spin liquid ground state. This results in a decrease of both resistivity and the current or voltage fluctuations after irradiation.

[1] PRL 115, 077001 (2015)

[2] PRL 114, 216403 (2015)