Galvanomagnetic methods of Curie temperature determination in (Ga,Mn)As

Abstract We critically discuss various experimental methods to determine Curie temperature T C of (Ga,Mn)As thin layers or other conducting magnetic materials by means of electric charge transport measurements. They all base on the influence of sample magnetization on the magnetoresistivity tensor ρ and are an alternative to the method based upon an analysis of the temperature derivative of the sample resistance (Novak et al., 2008). These methods can be applied even when standard SQUID magnetometers are difficult or impossible to use – for example for extremely small samples or in the case of experiments performed at very specific physical conditions, e.g. at high hydrostatic pressure inside the clamp cell. We show that the use of the so called Arrott plot prepared with the use of high magnetic field isotherms ρ xx ( H 0 ) , ρ xy ( H 0 ) ( H 0 – external magnetic field) may lead to substantial (of the order of 10 K) divergence of the obtained T C values depending on the assumptions which are necessary to make in this case and depending on the direction of a magnetic anisotropy easy axis. We also propose a number of ways how to obtain, basing on low magnetic field isotherms ρ xx ( H 0 ) , ρ xy ( H 0 ) , clear and characteristic features which are closely related to the ferromagnetic–paramagnetic phase transition.