Programmable oxide heterostructures.

 

Ho Nyung Lee

 

Oak Ridge National Laboratory, Oak Ridge, TN 37831

 

Epitaxy of complex-oxide thin films and heterostructures provides an immense challenge to design novel materials system, which enables us to explore previously unavailable phase space regions. We have established a growth technique to control complex oxides at the level of unit cell thickness by pulsed laser epitaxy. The atomic-scale growth control enables to assemble the building blocks to a functional system in a programmable manner, yielding many intriguing physical properties that cannot be found in bulk counterparts. In this talk, examples of artificially designed, programmable complex oxide heterostructures will be presented, highlighting the importance of interfacial coupling of energy quanta across and along the atomically well-defined interface. The main topics includes(1) fast, reversible redox reactions in epitaxial ‘oxygen sponges’ for oxide catalysts and energy storage1,2, (2) ferroelectric modulation of interfacial phases of correlated oxides3,4, and (3) strain control of ferroic properties, ionic conduction, and electrochemical behaviors in perovskite oxides5-9.

 

References:

(1)                 H. Jeen, W. S. Choi, M. D. Biegalski, I. C. Tung, J. W. Freeland, D. Shin, H. Ohta, M. F. Chisholm, and H. N. Lee, Reversible redox reactions in an epitaxially stabilized SrCoOx oxygen sponge, Nature Mater. 12, 1057 (2013).

(2)                 W. S. Choi, H. Jeen, J. H. Lee, S. S. A. Seo, V. R. Cooper, K. M. Rabe, and H. N. Lee, Reversal of the lattice structure in SrCoOx epitaxial thin films studied by real-time optical spectroscopy and first-principles calculations, Phys. Rev. Lett. 111, 097401 (2013).

(3)                 L. Jiang, W. S. Choi, H. Jeen, S. Dong, Y. S. Kim, S. V. Kalinin, E. Dagotto, T. Egami, and H. N. Lee, Tunneling electroresistance induced by interfacial phase transitions in ultrathin oxide heterostructures, Nano Lett. 13, 5837 (2013).

(4)   M. F. Chisholm, W. Luo, M. P. Oxley, S. Pantelides, and H. N. Lee, Atomic-scale compensation phenomena at polar interfaces, Phys. Rev. Lett. 105, 197602 (2010).

(5)                 H. Jeen, W. S. Choi, J. W. Freeland, H. Ohta, C. U. Jung, and H. N. Lee, Topotactic phase transformation of the brown millerite SrCoO2.5 to the perovskite SrCoO3-δ, Adv. Mater. 25, 3651 (2013).

(6)                 W. S. Choi, S. Lee, V. Cooper, and H. N. Lee, Fractionally δ-doped oxide superlattices for higher carrier mobilities, Nano Lett.12, 4590 (2012).

(7)                 H. Jeen, Z. Bi, W. S. Choi, C. A. Bridges, M. P. Paranthaman, and H. N. Lee, Orienting oxygen vacancies for fast catalytic reaction, Adv. Mater.25, 6459 (2013).

(8)                 H. N. Lee, S. M. Nakhmanson, M. F. Chisholm, H. M. Christen, K. M. Rabe, and D. Vanderbilt, Suppressed dependence of polarization on epitaxial strain in highly polar ferroelectrics, Phys. Rev. Lett.98, 217602 (2007).

(9)   H. N. Lee, H. M. Christen, M. F. Chisholm, C. M. Rouleau, and D. H. Lowndes, Strong polarization enhancement in asymmetric three-component ferroelectric superlattices, Nature, 433, 395 (2005).

(10)                       Research sponsored by the Materials Sciences and Engineering Division, Office of Basic Energy Sciences, U.S. Department of Energy.

 

 

Host. Prof. D. Vanderbilt