Fig. 4: Phase diagram of LuFe2O4 under pressure.

a Relative reduction of lattice parameters a and c by increased pressure measured between 0.8 and 12.6 GPa. b Evolution of in-plane incommensurate CO wave vector δ by pressure. δ is defined by (1/3+δ, 1/3+δ) in CO-AP and (1/3−δ, 1/3−δ) in CO-2D. The commensurate CO wave vector (1/4, 1/4) of CO-HP is represented by δ = 1/12. c The pressure dependence of XMCD spectral weight. d The pressure dependence of relative enthalpies between the charge order phases mentioned in Figs. 2 and 3d–f. (ferri (ferrimagnetic), AFM (antiferromagnetic)).