Thin film chromium oxide perovskites

Seed 1
Riccardo Comin

During the second year of this project, we have elucidated the magnetic ground state of layered Cr-based oxide perovskite Sr2CrO4.  We now demonstrate that this compound is not only isostructural to high-Tc superconducting parent compound La2CuO4, but also shares the same magnetic ground state. This raises exciting new prospects for harnessing new strongly-correlated electronic phases of matter.

Our recent X-ray scattering measurements were performed at the Cr-K resonance (6 keV) revealed the existence of magnetic Neel order below 110 K (figure panels A and B) and, most surprisingly, of stripe-like ordering below 50 K.  These two electronic orders appear to coexist at low temperature, setting a precedent for a new phenomenon among transition metal oxides In future years, we plan to chart out the out the temperature-doping phase diagrams of Sr2CrO4 and to synthesize new chromite materials with varying dimensionality.

Momentum space signatures of Neel (A) and stripe (B) order in Sr2CrO4, and corresponding temperature dependence of Neel (C) and stripe (D) order parameters.


In summer 2018 (Jun-Aug), we offered a few research projects to visiting teachers and students, in particular:

  • We hosted Juan Hincapie, a college student from Roxbury Community College for summer research (REU program) on electronic transport measurements in quantum solids.
  • We hosted Wendy Moy, a middle school teacher (Lexington middle school) for summer research (RET program) on the synthesis of optoelectronic materials.

Left: Middle school teacher Wendy Moy is preparing the ‘mother solution’ to crystallize lead halide perovskite compound CH3NH3PbBr3, using the technique of solvent annealing. This material has made the headlights as a potential new candidate for green-emitting light-emitting diodes with high efficiencies. Right: Community college student Juan Hincapie is assembling a test sample cell inside a cryostat. Juan’s project focused on developing the apparatus and control electronics to measure resistivity at cryogenic temperatures (4 K) using the four-point-probe technique.