Quantum phase transition in few layer NbSe<sub>2</sub> probed through quantized conductance fluctuations

ORAL

Abstract

We present the first experimental observations of a quantum phase transition (QPT) between two distinct charge density wave (CDW) phases in 2-dimensional 2H-NbSe2. Our studies were performed on suspended, ultra-thin 2H-NbSe2 devices fabricated on piezoelectric substrates. We establish, through sensitive conductance fluctuation spectroscopy, that on varying the strain the system undergoes a QPT between the familiar triangular 3Q CDW phase and a novel linear 1Q CDW phase. With the help of mean-field calculations, these observations can be explained as to arise from dynamical phase transition between the two CDW states. 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 (QCP). The results resolve a long-standing mystery of the anomalously large spectroscopic gap in the density of states of 2H-NbSe2 measured through tunneling spectroscopy.

*We acknowledge financial support from Nanomission DST [project SR/NM/NS-35/2012]; SERB DST; Indo-French Centre for the Promotion of Advanced Recearch (CEFIPRA); CSIR, MHRD, Govt. of India and DST, (Young Scientist) [SERB No: YSS/2015/001286].

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Presenters

  • Aveek Bid

    • Department of Physics, Indian Institute of Science

Authors

  • Hemanta Kundu

    • Department of Physics, Indian Institute of Science

  • Sujay Ray

    • Department of Physics, Indian Institute of Science

  • Kapildeb Dolui

    • Department of Physics, Indian Institute of Science
    • Physics and Astronomy, Univ of Delaware

  • Vivas Bagwe

    • Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research

  • Palash Choudhury

    • School of Natural Sciences, Mahindra École Centrale

  • S Krupanidhi

    • Materials Research Centre, Indian Institute of Science

  • Tanmoy Das

    • Department of Physics, Indian Institute of Science
    • Physics, Indian Institute of Science
    • Physics Department, Indian Institute of Science
    • Physics, Indian institute of science
    • IISc

  • Pratap Raychaudhuri

    • Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research
    • Tata Institute of Fundamental Research

  • Aveek Bid

    • Department of Physics, Indian Institute of Science