$\mu \mathrm{SR}$ and magnetometry study of superconducting 5% Pt-doped ${\mathrm{IrTe}}_2$

We present magnetometry and muon spin rotation $\left(\mu \mathrm{SR}\right)$ measurements of the superconducting dichalcogenide ${\mathrm{Ir}}_{0.95}{\mathrm{Pt}}_{0.05}{\mathrm{Te}}_2$. From both sets of measurements, we calculate the penetration depth and thence superfluid density as a function of temperature. The temperature dependence of the superfluid densities from both sets of data indicate fully gapped superconductivity that can be fit to a conventional $s$-wave model and yield fitting parameters consistent with a BCS weak coupling superconductor. We therefore see no evidence for exotic superconductivity in ${\mathrm{Ir}}_{0.95}{\mathrm{Pt}}_{0.05}{\mathrm{Te}}_2$.

Figure 1

Magnetization measurements on a polycrystalline sample of ${\mathrm{Ir}}_{0.95}{\mathrm{Pt}}_{0.05}{\mathrm{Te}}_2$ measured in a field of 300 Oe after cooling in zero field. (Inset) Upper critical field of the polycrystalline sample. The red line shows a linear fit to the critical field.

Figure 2

SR $\mu \mathrm{SR}$ time spectra of ${\mathrm{Ir}}_{0.95}{\mathrm{Pt}}_{0.05}{\mathrm{Te}}_2$ measured in an applied field of 300 Oe at (a) $T=0.03$, (b) 1, and (c) 2 K. (d) Fourier transform of the $\mu \mathrm{SR}$ data collected in an applied field of 300 Oe at $T=0.03$ K. The inset in (d) shows the theoretical field distribution of a superconductor using the London model [29].

Figure 3

Parameters used to fit Eq. (1) to the $\mu \mathrm{SR}$ data measured in a field of 300 Oe transverse to the muon spins. (a) and (b) show the individual relaxation rates ${\sigma }_1$ and ${\sigma }_2$. (c) shows the average sample internal field. (d) shows the effective total width of the frequency distribution [see Eq. (3)].

Figure 4

Penetration depth determined from magnetometry and $\mu \mathrm{SR}$ measurements. Green circles are from magnetometry of a single crystal with $H \parallel$ C axis. Red triangles are from magnetometry with $H \perp$ C axis. Blue squares are from $\mu \mathrm{SR}$ using a Gaussian fit.

Figure 5

Magnetization measurements on a single-crystal sample of ${\mathrm{Ir}}_{0.95}{\mathrm{Pt}}_{0.05}{\mathrm{Te}}_2$ in a field of 50 Oe applied (a) perpendicular to the C axis and (b) parallel to the C axis. Closed circles show measurements after cooling in zero applied field and open circles show measurements after cooling with the field applied.

Figure 6

(a) and (b) Magnetization vs internal field curves measured at 0.5 K (black squares) and 2 K (red circles) for (a) $H \parallel$ C axis and (b) $H \perp$ C axis. (c) and (d) Magnetization vs $\ln \left(H\right)$ curves along with linear fits to the high-field region (solid lines) measured at 0.5 K (black squares) and 2 K (red circles) for (c) $H \parallel$ C axis and (b) $H \perp$ C axis.

Figure 7

Normalized superfluid density determined from magnetization and $\mu \mathrm{SR}$ measurements. Red triangles are from magnetometry of a single crystal with $H \parallel$ C axis. Green circles are from magnetometry with $H \perp$ C axis. Blue squares are from the $\mu \mathrm{SR}$ data. Solid lines show BCS fits to the data using Eq. (7).