Proximity of superconducting LaCoSi to a ferromagnetic quantum critical point

Abstract

The physical characteristics of the 4 K superconductor LaCoSi are studied using first-principles density functional theory inside the local density approximation (LDA) framework. We discover that LDA predicts a ferromagnetic ground state for LaCoSi, which is in disagreement with the experiments. Even though LDA rarely overestimates the local magnetic moment associated with the magnetic ion in itinerant systems, such occurrences highlight the significance of spin fluctuations in the system. In this view, the Ginzburg–Landau free energy expansion and its variation as a function of pressure are used to calculate the amplitude of the zero-point fluctuations. Based on our calculations, we contend that the superconductivity associated with LaCoSi is closely related to a ferromagnetic quantum critical point, making it an intriguing candidate for the category of quantum materials.