High-pressure polymorph of LuFe2O4 with room-temperature antiferromagnetic order

International audienceBranded for its potential electronic ferroelectricity, charge-ordered LuFe2O4 has a layered Fe triangular framework, whose topology is a source of degeneracy, both at the charge and spin levels. Here we present an in-depth characterization of LuFe2O4-hp, the high-pressure (hp) polymorph of LuFe2O4, using electron, x-ray, and neutron diffraction, combined with transport and magnetization measurements. We show that LuFe2O4-hp is characterized by a misfit-related monoclinic structure, accommodating a buckled triangular [Lu](infinity) layer and two shifted adjacent rectangular [Fe](infinity) planes belonging to a distorted rock salt-type layer. The release of the geometric frustration of the Fe magnetic lattice in the hp form leads to collinear antiferromagnetic ordering at T-N = 380 K. Possible coexistence of charge and magnetic orders in this material opens research pathways for the design of tunable multifunctional devices using high-pressure techniques