In condensed matter physics, an Arrott plot is a plot of the square of the magnetization of a substance, against the ratio of the applied magnetic field to magnetization at one (or several) fixed temperature(s). Arrott plots are an easy way of determining the presence of ferromagnetic order in a material. They are named after American physicist Anthony Arrott who introduced them as a technique for studying magnetism in 1957.
where , the magnetization, is the order parameter, is the applied magnetic field, is the critical temperature, and are arbitrary constants.
Close to the phase transition, this gives a relation for the magnetization order parameter:
where is a dimensionless measure of the temperature.
Thus in a graph plotting vs. for various temperatures, the line without an intercept corresponds to the dependence at the critical temperature. Thus along with providing evidence for the existence of a ferromagnetic phase, the Arrott plot can also be used to determine the critical temperature for the phase transition.
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