Quantum phase transition in few-layer NbSe${}_2$ probed through quantized conductance fluctuations

Abstract

We present the first observation of dynamically modulated quantum phase transition (QPT) between two distinct charge density wave (CDW) phases in 2-dimensional 2H-NbSe${}_2$. There is recent spectroscopic evidence for the presence of these two quantum phases, but its evidence in bulk measurements remained elusive. We studied suspended, ultra-thin \nbse 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 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 NbSe${}_2$.

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Cited by in corpus (10)

• Atomic-Scale Strain Manipulation of a Charge Density Wave
• Low-Frequency Noise and Sliding of the Charge Density Waves in Two-Dimensional Materials
• Topological Landscape of Competing Charge Density Waves in 2H-NbSe2
• Low-Frequency Noise Spectroscopy of Charge-Density-Wave Phase Transitions in Vertical Quasi-2D Devices
• Transition from three- to two-dimensional Ising superconductivity in few-layer NbSe2 by proximity effect from van der Waals heterostacking
• Probing defect states in few-layer MoS${}_2$ by conductance fluctuation spectroscopy
• Conductivity noise across temperature driven transitions of rare-earth nickelate heterostructures
• Exceptionally Slow, Long Range, and Non-Gaussian Critical Fluctuations Dominate the Charge Density Wave Transition
• Correlated carrier dynamics in a superconducting van der Waals heterostructure
• Hidden electronic phase in strained few-layer 1T-TaS2