Tuning superconductivity in Nb$_{2}$Pd$_{0.81}$S$_{5}$ using applied pressure and uniaxial strain

Nb$_{2}$Pd$_{0.81}$S$_{5}$ is a recently reported transition metal-chalcogenide superconductor (T$_{\mathrm{c}}$ $\sim$ 6.6 K) with unusually large upper critical fields (H$_{\mathrm{c}}$ \textgreater 37 T for H // b) [1]. We present electrical resistivity measurements under applied pressure for this compound, where a piston cylinder cell was used with Daphne 7474 oil as the pressure transmitting medium. These measurements reveal that the superconducting transition temperature abruptly increases to 8.5 K for P \textless 2 kbar, but additional pressure (up to 16 kbar) has little effect on T$_{\mathrm{c}}$. This result may indicate that while the electronic state of this compound is sensitive to strain, it is only weakly affected by hydrostatic pressure. This viewpoint is supported by subsequent experiments where application of Daphne oil or N-grease to the crystal surface results in an increase of T$_{\mathrm{c}}$ to 8 K. In order to systematically disentangle the influence of pressure and strain, we will present results from resistivity measurements where the sample is uniaxially strained using a piezo-stack (``elastoresistance'') along the b direction. \\[4pt] [1] Q.Zhang, et. Al.,''Superconductivity with extremely large upper critical fields in Nb$_{2}$Pd$_{0.81}$S$_{5}$,'' Scientific Reports(2013).