Extended Data Figure 3: Magnetic characterization of the (LuFeO3)m/(LuFe2O4)n superlattices.
From: Atomically engineered ferroic layers yield a room-temperature magnetoelectric multiferroic
a, M–T curves for a series of (LuFeO3)m/(LuFe2O4)1 superlattices cooled in a 1-kOe field. b, M–T curves for a series of (LuFeO3)1/(LuFe2O4)n superlattices cooled in a 1-kOe field. c, The “excess magnetization” is found by subtracting the bulk magnetization of the LuFe2O4 and LuFeO3 from the measured moment. It is plotted normalized to the number of iron atoms in the LuFe2O4 layers in the sample. The composition is plotted according to the fraction of iron atoms in the LuFeO3 layers in the (LuFeO3)m(LuFe2O4)n structure. d, Loops of the magnetization M as a function of the magnetic field H for the (LuFeO3)9/(LuFe2O4)1 superlattice. The M–H loop at 300 K has a distinctly different shape that is more reminiscent of the 250-K loop, demonstrating that ferromagnetic (or ferrimagnetic) fluctuations still exist at 300 K even if the entire film is not ferromagnetic (or ferrimagnetic). e, The saturation magnetization of the (LuFeO3)9/(LuFe2O4)1 superlattice at 70 KOe as a function of temperature. Although the remanent magnetization, as measured by the field-cooled curve, disappears around the Curie temperature of 281 K, ferromagnetic (or ferrimagnetic) fluctuations remain in this sample to temperatures above room temperature.
