A Quantitative Arrott Analysis Methodology for Magnetic Susceptibility of Microscale Ferromagnetic Nanoflakes

Probing magnetic susceptibility of a microsized ferromagnet is a long-standing problem in condensed matter physics. Among various measuring methods for magnetic susceptibility including vibrating sample magnetometry and superconducting quantum interference device magnetometry, almost all require large-scale bulk samples or thick films. However, the quantitative measurement for magnetic susceptibility on a microscale nanoflake is a great challenge. Here, we demonstrate a new analysis method to quantitatively evaluate the magnetic susceptibility of a microscale ferromagnetic nanoflake. Based on the Arrott plot of magnetization isotherms obtained from anomalous Hall resistance, we achieve an in situ evaluation of the value of magnetic susceptibility of a microscale ferromagnetic Fe₅GeTe₂ nanoflake, identification of the out-of-plane and in-plane magnetization, and investigation of the magnetic anisotropy transition with quantifying critical exponents. Our method reveals critical information on magnetic phase transition in microscale ferromagnetic materials, providing deep insight into spin dynamics of correlated electron systems.