Wacky oxides: Rich properties in search of devices

Until recently, the word “oxide” could only mean one thing to the device research community-SiO₂. But as is being increasingly realized, oxides are an exciting class of electronic materials in their own right. Oxides exhibit the full spectrum of electronic, optical, and magnetic behavior: insulating, semiconducting, metallic, superconducting, ferroelectric, pyroelectric, piezoelectric, ferromagnetic, multiferroic, and non-linear optical effects are all possessed by structurally-compatible oxides. Further, the properties of a given composition can change drastically as it goes through phase transitions that can be driven by temperature, strain, electric field, magnetic field, light, etc., resulting in huge property coefficients, metal-insulator-transitions, electrical and optical control of magnetism, etc. The unparalleled variety of physical properties of oxides holds tremendous promise for electronic applications, but there is also a danger that oxides may become the immutable “material of the future” that never makes it into a real device.