Pressure-induced superconducting and structural properties of noncentrosymmetric LaPtGe

The compounds LaPt(Ge, Si) and LaNiSi are exciting platforms to investigate the possibility of topological superconductivity due to their noncentrosymmetric (NCS) crystal structure and the presence of nodal-line Weyl electronic dispersion. Here, we investigate the effect of pressure on the superconducting and structural properties of LaPtGe through resistivity and x-ray-diffraction (XRD) studies. Our findings reveal a two-step increase of superconducting transition temperature $({T}_c)$ from 3.06 K (0 GPa) to 3.94 K (6 GPa), with the rate of 0.071 K/GPa up to \ensuremath{\sim}3 GPa, and beyond that, it increases to a 2.5 times higher rate of 0.183 K/GPa up to 6 GPa. High-pressure XRD confirms the structural stability up to 7.82 GPa, though a change in lattice compression behavior is observed. The two distinct compressions of unit-cell parameters are observed with the bulk modulus of \ensuremath{\sim}144 GPa (below 3 GPa) and \ensuremath{\sim}162 GPa (above 3 GPa), derived using the Birch-Murnaghan equation of state. Magnetotransport studies up to 2.45 GPa show an increase in the upper critical field $[{H}_c2(0)]$ from 0.7 to 0.92 T, with a positive curvature of ${H}_c2(T)$, suggesting the possibility of multigap superconductivity in LaPtGe, similar to LaPtSi. Further, it indicates that the lattice compression effects primarily drive the enhancement of ${T}_c$, and it may be due to the modifications in the density of states at the Fermi level. Our results provide insights into pressure-tuned superconductivity mechanisms in NCS compounds.