Magnetization results of twinned EuFe₂As₂. Field dependence of magnetization with the H parallel to ab plane at various temperatures (a) and the corresponding d M/H (b). The expanded M(H) plot at 4 K is shown in the inset of (a). The red and blue arrows represent the measuring setup with increasing field and decreasing field, respectively. Inset of (b) shows the magnetic phase diagram for twinned EuFe₂As₂, the data about T_Curie gets from the neutron scattering result.^[25] (c) Sketch of the magnetic field dependent twin distribution and spin configuration of EuFe₂As₂ below T_Eu.