Symmetry Mismatch Controls Magnetism ​in a Ferroelastic Film​

February 2, 2020
Symmetry Mismatch Controls Magnetism ​in a Ferroelastic Film​
(a) Schematic illustration of PNR geometry measured on LCO film showing magnetization enhanced away from the interfaces. (b) PNR data for two polarizations. (c) Fitted nuclear SLD. (d) Magnetic SLD.​

Scientific Achievement

The magnetization depth profile of LaCoO3 (LCO) films shows that pressure reduces the magnetization, confirming that a symmetry mismatch at the interface leads to the  unexpected ferromagnetism (FM).​

Significance and Impact

The results give new insights into the control of magnetism in thin films of  ferroelastic materials, pointing to next generation devices such as strain sensors.​

Research Details

  • Polarized neutron reflectometry (PNR) was measured using a new pressure cell.​
  • The origin of FM was found to be higher spin state Co3+ in low density regions away from the mismatched interface; pressure increases the density producing non-magnetic low spin Co3+.​

E.J. Guo et al., Physical Review Letters 122, 187202 (2019).​