EuFe₂As₂ crystal and magnetic structure (Eu atoms (yellow) and spins (blue), Fe atoms (green) and spins (red), and As atoms (celadon)), and the spin configuration of Eu²⁺ dependent on an external magnetic field along a (a), b (b), and c direction (c), respectively. The black arrows are the applying external magnetic field and the length of the black arrows means the magnitude of the magnetic field. The gray arrows are the original spins of Eu²⁺.