Dimensionality switching and superconductivity transition in dense 1T−HfSe2

Abstract

The quest for new transition metal dichalcogenides (TMDs) with outstanding electronic properties is a particularly significant and interesting subject. The use of nonconventional methods of materials synthesis, especially pressure engineering, shows great potential for breakthrough discoveries in TMDs. Here, we employ the high-pressure techniques to successfully realize the transformation of two-dimensional semiconductor into three-dimensional superconducting states in 1T−HfSe2. We unambiguously demonstrate that the enhancement of the interlayer coupling and the bonding between interlayer Se-Se atoms contribute to the emergence of nonlayered C2/m and I4/mmm phases. The discovered three-dimensional (3D) structures present excellent superconductivity compared to the original layered structure, and the superconducting critical temperature reaches a maximum of 5.8 K at around 50 GPa. Theoretical calculations reveal that the realization of superconductivity in these two 3D structures is related to the increase in the density of states at the Fermi surface [N(ɛf)]. The present results in HfSe2 may provide a platform for our deep understanding of the relationship among dimensionality, structure, and superconductivity phenomena in TMDs.

Source-reported materials — not catalogue approval

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