Surface magnetism and proximity effects in hexaboride thin films
Abstract
The unexpected ferromagnetism in alkaline hexaborides has attracted extensive research efforts. The exceptionally high Curie temperature sustained by very low density of magnetic moments is yet to be clearly understood. Here, we report the magnetic properties studied in CaB6 and SrB6 thin films and their heterostructures with SmB6 grown by pulsed laser deposition. A coexistence of ferromagnetic and superparamagnetic orders with 2D-type magnetic anisotropy was observed in CaB6 and SrB6. Boron deficiency and closely correlated local oxidization were found at the film surface that contacts air and its interface with the oxide substrate. These results suggest that the magnetism observed is likely generated by two thin surface/interface layers with high concentration of boron vacancies which are energetically stabled by oxygen cation. Additionally, clear suppression of the superconductivity proximity effect in SmB6 film was observed when SmB6 was grown on top of the magnetic CaB6. Such results demonstrate the interesting perspective of engineering multifunctional heterostructures by coupling the surface magnetic layer with the diversity of other hexaboride materials.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Mar 06, 2017
- Source ID
- 10.1063/1.4978433
Entities
People
- Chang-Beom Eom
- Cheng Cen
- Qiang Wang
- Yanjun Ma
Organizations
- Air Force Office of Scientific Research
- National Science Foundation
- United States Department of Energy
- University of Wisconsin–Madison
- West Virginia University