In a recent study, researchers combined multiple experimental probes and discovered pressure-induced semimetal-to-superconductor transition in a Dirac topological semimetal zirconium pentatelluride (ZrTe₅) compound.

Three-dimensional Dirac semimetals attract a lot of advanced researches which mostly focus on many exotic properties and their association with crystalline and electronic structures under extreme conditions (pressure, temperature, magnetic field, etc.). As one of the fundamental state parameters, high pressure is an effective clean way to tune lattice as well as electronic states, especially in quantum states, thus their electronic and magnetic properties.

As a new type of topological materials, ZrTe₅ shows many exotic properties under extreme conditions. Utilizing resistance and ac magnetic susceptibility measurements under high pressure, researchers found while the resistance anomaly near 128 K is completely suppressed at 6.2 GPa, a fully superconducting transition emerges. The superconducting transition temperature T_c increases with applied pressure, and reaches a maximum of 4.0 K at 14.6 GPa, followed by a slight drop but remaining almost constant value up to 68.5 GPa. At pressures above 21.2 GPa, a second superconducting phase with the maximum T_c of about 6.0 K appears and coexists with the original one to the maximum pressure studied in this work (Fig. 1).

In situ high-pressure synchrotron X-ray diffraction and Raman spectroscopy combined with theoretical calculations indicate that the observed two-stage superconducting behavior is correlated to the structural phase transition from ambient Cmcm phase to high-pressure C2/m phase around 6 GPa, and to a mixture of two high-pressure phases of C2/m and P-1 above 20 GPa. The combination of structure, transport measurement and theoretical calculations enable a complete understanding of the emerging exotic properties in three-dimensional topological materials under extreme environments.

This study was jointly conducted by researchers in High Magnetic Field Laboratory of Chinese Academy of Sciences (CHMFL), Nanjing University, Center for High Pressure Science & Technology Advanced Research (HPSTAR) in Shanghai and Carnegie Institution of Washington.

This work entitled Pressure-induced superconductivity in a three-dimensional topological material ZrTe5 was published in PNAS.

Figure 1. Temperature-pressure phase diagram of ZrTe5 single crystal. (Image by ZHOU Yonghui)

YANG Zhaorong, Principal Investigator

High Magnetic Field Laboratory, Chinese Academy of Sciences

Hefei 230031, Anhui, China

Tel: 0551-65595125

Email: zryang@issp.ac.cn