Quantum phases in 1T-TaS₂: from bulk to atomically-thin layers and van der Waals heterostructures.

Quantum materials exhibiting magnetic frustration are connected to diverse phenomena, including high T_c superconductivity, topological order, and quantum spin liquids (QSLs). A QSL is a quantum phase (QP) related to a quantum-entangled fluid-like state of matter. A relevant example is provided by 1T-TaS₂, which shows a multifaceted electronic and magnetic scenario due to the existence of several charge density waves (CDW) configurations, including quantum hidden phases, superconductivity and even quantum spin liquid phases, that are highly dependent on the out-of-plane stacking of the CDW.

Here, we discuss both bulk and atomically thin-layers of 1T-TaS₂. For bulk, we report on combined temperature-dependent muon spin relaxation and specific heat measurements for this triangular-lattice QSL candidate material that provide evidence for competing QPs [1]. In addition, atomically thin-layers of 1T-TaS₂ are integrated in vertical van der Waals heterostructures based on few-layers graphene and NbSe₂ contacts and their electrical transport properties are measured. Different activation energies in the conductance and a gap at the Fermi level are clearly observed [2, 3]. These features make 1T-TaS₂ a potential candidate for hosting multiple QSL crossovers.

1. npj Quantum Materials 6, 69 (2021).

2. ACS Nano 15, 7, 11898 (2021).

3. Adv. Electron. Mater. 7, 2000987 (2021).