EMMD/Oxide MBE

Aim

To explore emergent behavior at the interfaces between complex oxides with distinct ground states, where reconstructions of spin, lattice and charge degrees of freedom give rise to novel collective states.

Team

Anand Bhattacharya, Steve May and Tiffany Santos with the oxide-MBE chamber in the CNM.

Anand Bhattacharya

Principal Investigator (CNM, MSD)

Steven May

Postdoc (MSD)

Tiffany Santos

Postdoc (CNM)

Tools

We have designed and commissioned an ozone-assisted molecular beam epitaxy (MBE) system, capable of synthesizing complex oxides with single-atomic layer precision. The system was built by DCA Instruments (Finland).

• Pure ozone as the oxidizing agent
• 10 differentially-pumped Knudsen cells
• 3-pocket electron-beam sources
• In situ reflection high energy electron diffraction (RHEED)
• Atomic flux monitoring by quartz crystal monitor
• Atomic Absorption Spectroscopy for real time in situ flux monitoring

Highlights

CNM News: Frontiers of Complex Oxides Workshop -- Poster Prize

Scanning transmission electron micrograph of alternating layers of LaMnO₃ (light contrast) and SrMnO₃ (dark contrast), forming a superlattice that is coherently strained to a SrTiO₃ substrate. Image by Amish Shah, a collaborator at UIUC.

X-ray reflectivity of LaMnO₃/SrMnO₃ superlattices with different Sr content (x), made by depositing single unit cell (~0.4 nm) layers of SrMnO₃ and LaMnO₃. The superlattice peaks in the reflectivity show that these films are exceptionally smooth, with atomically abrupt interfaces and minimal intermixing.

Recent Publications

• S. J. May, T. S. Santos and A. Bhattacharya, "Onset of Metallic Behavior in Strained (LaNiO₃)_n/(SrMnO₃)₂ Superlattices," submitted to Phys. Rev. B

• Tiffany S. Santos, Steven J. May, J. Lee Robertson and Anand Bhattacharya, "Stabilizing an Antiferromagnetic Metal in La_1-xSr_xMnO₃ by Digital Synthesis, manuscript in preparation

• S. J. May, A. B. Shah, S. G. E. te Velthuis, M. R. Fitzsimmons, J. M. Zuo, X. Zhai, J. N. Eckstein, S. D. Bader and A. Bhattacharya, "Magnetically Asymmetric Interfaces in a LaMnO₃/SrMnO₃ Superlattice due to Structural Asymmetries," Phys. Rev. B 77, 174409 (2008).

• A. Bhattacharya, S. J. May, S. G. E. te Velthuis, M. Warusawithana, X. Zhai, Bin Jiang, J.-M. Zuo, M. R. Fitzsimmons, S. D. Bader and J. N. Eckstein, "Metal-Insulator Transition and Its Relation to Magnetic Structure in (LaMnO₃)_2n/(SrMnO₃)_n Superlattices," Phys. Rev. Lett. 100, 257203 (2008).

• Serban Smadici, Peter Abbamonte, Anand Bhattacharya, Xiaofang Zhai, Bin Jiang, Andrivo Rusydi, James N. Eckstein, Samuel D. Bader and Jian-Min Zuo, "Electronic Reconstruction at SrMnO₃-LaMnO₃ Superlattice Interfaces," Phys. Rev. Lett. 99, 196404 (2007).