Enhanced superconductivity in the Se-substituted 1T-${\mathrm{PdTe}}_2$

The two-dimensional transition metal dichalcogenide ${\mathrm{PdTe}}_2$ has recently attracted much attention due to its phase coexistence of a type-II Dirac semimetal and type-I superconductivity. Here we report a 67% enhancement of the superconducting transition temperature in 1T-PdSeTe in comparison to that of ${\mathrm{PdTe}}_2$ through partial substitution of Te atoms by Se. The superconductivity has been unambiguously confirmed by the magnetization, resistivity, and specific heat measurements. 1T-PdSeTe shows type-II superconductivity with large anisotropy and a nonbulk superconductivity nature with a volume fraction of $\approx 20\%$ estimated from magnetic and heat capacity measurements. 1T-PdSeTe expands the family of superconducting transition metal dichalcogenides and thus provides additional insights for understanding superconductivity and topological physics in the 1T-${\mathrm{PdTe}}_2$ system

Figure 1

(a) XRD pattern and Rietveld refinement of 1T-PdSeTe at room temperature. Vertical marks (green bars) stand for positions of Bragg peaks. The inset shows the XRD pattern and optical image on the millimeter-size grid of the easily exfoliated flake. Ball and stick model of the crystal structure of 1T-PdSeTe showing (b) the side view and (c) top view.

Figure 2

Temperature dependence of magnetic susceptibility measured in both the ZFC mode and FC mode with an external field of 5 Oe (a) parallel to the crystallographic $c$ axis and (b) perpendicular to the $c$ axis. (c) Magnetic hysteresis loop of 1T-PdSeTe at 2 K with external field parallel to the $c$ axis. (d) MHLs in the magnetic penetration process at 1.8, 2, and 4.5 K with external field parallel to the $c$ axis. The dashed line represents the slope of the perfect diamagnetism.

Figure 3

(a) Temperature dependence of resistivity for 1T-PdSeTe. The inset shows an enlarged view of the resistivity near the superconducting transition temperature. (b) Temperature dependence of resistivity for 1T-PdSeTe at zero field and various magnetic fields parallel to the $c$ axis. The inset shows the upper critical field $H_{c2}$ as a function of temperature. The red line represents the best fitting using the function described in the text.

Figure 4

Magnetic field dependence of the Hall resistivity${\rho }_{xy}$ for 1T-PdSeTe at various temperatures. The inset shows the temperature dependence of the Hall coefficient $R_H$.

Figure 5

Temperature dependence of specific heat under 0 T (solid circles) and 1 T (open circles). The red line represents the fitting using $C_p/T={\gamma }_n+{\beta T}^2$. The inset shows an enlarged view of the temperature dependence of specific heat below 3 K. $T_c$ is obtained utilizing the equal-area construction method for specific heat data.

Figure 6

(a) Temperature dependence of magnetization for 1T-PdSeTe near the superconducting phase transition with external magnetic field parallel to the $c$ axis. The inset shows an enlarged view of the temperature-dependent magnetization of S2 and S3 in the ZFC mode. (b) Temperature dependence of normalized resistivity for 1T-PdSeTe synthesized under different cooling conditions.