Thin Film Chromium Oxide Perovskites

Intellectual Merit
During the first year of this project, we have successfully developed a procedure to produce thin films of layered Cr-based oxide perovskite Sr2-xLaxCrO4 (SLCO).  This compound, which is isostructural to high-Tc superconductor La2Sr2-xCuO4, has been proposed to harbor a flurry of electronic ordering phenomena, including a spin-density-wave and orbital order.

SLCO films have been grown on different substrates (LAO, STO) and characterized with a series of techniques (XRD, SEM, TEM, magnetometry). More recently, our group performed resonant magnetic scattering measurements that confirmed, for the very first time in these systems, the presence of magnetic ordering at wavevectors Q=(±0.13,±0.13,5.3), as shown in the figure. The spins order below ~200 K, a temperature where we have also observed the potential signatures of concurrent orbital ordering.


Broader Impact
The broader impacts of this project connect to its interdisciplinary nature, at the intersection of materials science and advanced X-ray characterization. The scientific work serves as a training platform for the use of resonant X-ray spectroscopies for different generations of researchers (undergraduate, graduate, and postdoctoral), a possibility which is new and timely as it leverages the advent of X-ray facilities where these experimental methods can be finally used by a broad community of users.

Figure: MIT sophomore student Kevin Limanta (left) mounting samples at ISR beamline (NSLS-II, BNL) with MIT postdoctoral associate Zhihai Zhu (center) and NSLS-II beamline scientist Christie Nelson (right).