Argonne National Laboratory

Upcoming Events

The Dead Layer and Critical Behavior of La23 Sr13 MnO3 Ultra Thin Film

Series 
Materials Science Seminar
Presenter 
Zhaoliang Liao, Louisiana State University
February 7, 2013 2:00PM to 3:00PM
Location 
Building 223, Room S105
Type 
Seminar
Abstract:
Dead layer - the insulating behavior in ultrathin films of metallic oxides - is an intriguing property of thin TMO films. The question is, is this effect caused by dimensional confinement, or by the interface, strain, segregation, impurity, or stoichiometry.

Utilizing UHV Laser-MBE growth technique, we have systematically studied the thickness-dependence of structure/properties for La23 Sr13 MnO3 (LSMO) on SrTiO3(001) by using in-situ characterization such as LEED, XPS and STM, and ex-situ transport measurements.

With optimized growth conditions to minimize the oxygen deficiency (oxygen non-stoichiometry), we were able to focus on the other effects associated with the dead layer. In this talk, I will summarize our recent results on the dead layer of LSMO by showing that the dimensionality/structure effects play key role in determining the dead layer.

With this optimized quality of ultrathin films, new critical behaviors emerge, such as the non-monotonic structure relaxation with thickness, the enhanced magnetoresistance effect and extreme sensitivity to strain at the critical thickness at 6 unit cells. These behaviors are proposed to correlate with subtle balance of different competing effects.

Supported by the US Department of Energy.