Magnetic collapse and electronic phase transitions at high pressure in transition metal oxides

Abstract

A review of electronic and magnetic phase transition in metal oxides with strong electron correlations (SEC) is given. The bandwidth control of the insulator gap is expected in the Hubbard model when the decreasing of the interatomic distance results in the bandwidth W( P) increase and at some critical value P c, W( P c)∼ U and the Mott–Hubbard gap disappears. The other situation takes place in transition metal boroxides FeBO 3 and GdFe 3(BO 3) 4, where the increase of crystal field parameter Δ( P) results in the high spin–low spin crossover.