Theoretical Calculations and Experimental Measurements on the Two-Component Au - Pt Alloys with Ultralow Magnetic Susceptibility

A solid-state material with ultralow magnetic susceptibility $\ensuremath{\chi}$ is the key material candidate in aeronautical devices and special targeted drugs. In this work, we design a series of two-component alloy samples ${\mathrm{Au}}_{1\ensuremath{-}x}{\mathrm{Pt}}_{x}$, and study their magnetic structures and susceptibilities by using the first-principles calculations within a spin-polarized relativistic Korringa-Kohn-Rostoker coherent potential approximation. Our theoretical results demonstrate that by controlling the ratio parameter $x$, ultralow magnetic susceptibilities ($\ensuremath{\chi}<{10}^{\ensuremath{-}6}\phantom{\rule{0.2em}{0ex}}{\mathrm{cm}}^{3}/\mathrm{mol}$) occur in $\mathrm{Au}\mathrm{Pt}$ alloys around the sample ${\mathrm{Au}}_{0.75}{\mathrm{Pt}}_{0.25}$. Following the theoretical calculations, several realistic $\mathrm{Au}\mathrm{Pt}$ alloy samples with ultralow magnetic susceptibilities are fabricated successfully in experiments, and the experimental measurements on magnetic susceptibilities are well consistent with our theoretical predications. This work not only provides us changes to study physical properties of the materials with ultralow magnetic susceptibility, but also constructs unique materials towards special device applications in TianQin project and others.