Quantum Phase Transition in Few-Layer NbSe2 Probed through Quantized Conductance Fluctuations

Kundu, Hemanta Kumar and Ray, Sujay and Dolui, Kapildeb and Bagwe, Vivas and Choudhury, Palash Roy and Krupanidhi, SB and Das, Tanmoy and Raychaudhuri, Pratap and Bid, Aveek (2018) Quantum Phase Transition in Few-Layer NbSe2 Probed through Quantized Conductance Fluctuations. In: PHYSICAL REVIEW LETTERS, 119 (22).

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Abstract

We present the first observation of dynamically modulated quantum phase transition between two distinct charge density wave (CDW) phases in two-dimensional 2H-NbSe2. There is recent spectroscopic evidence for the presence of these two quantum phases, but its evidence in bulk measurements remained elusive. We studied suspended, ultrathin 2H-NbSe2 devices fabricated on piezoelectric substrates-with tunable flakes thickness, disorder level, and strain. We find a surprising evolution of the conductance fluctuation spectra across the CDW temperature: the conductance fluctuates between two precise values, separated by a quantum of conductance. These quantized fluctuations disappear for disordered and on-substrate devices. With the help of mean-field calculations, these observations can be explained as to arise from dynamical phase transition between the two CDWstates. To affirm this idea, we vary the lateral strain across the device via piezoelectric medium and map out the phase diagram near the quantum critical point. The results resolve a long-standing mystery of the anomalously large spectroscopic gap in NbSe2.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW LETTERS
Additional Information:	Copy right for this article belongs to the AMER PHYSICAL SOC, ONE PHYSICS ELLIPSE, COLLEGE PK, MD 20740-3844 USA
Department/Centre:	Division of Chemical Sciences > Materials Research Centre Division of Physical & Mathematical Sciences > Physics
Date Deposited:	26 Dec 2017 06:03
Last Modified:	26 Dec 2017 06:03
URI:	http://eprints.iisc.ac.in/id/eprint/58423

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