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Title: Surface magnetism and proximity effects in hexaboride thin films

Here, 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 CaB 6 and SrB 6 thin films and their heterostructures with SmB 6 grown by pulsed laser deposition. A coexistence of ferromagnetic and superparamagnetic orders with 2D-type magnetic anisotropy was observed in CaB 6 and SrB 6. 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 SmB 6 film was observed when SmB 6 was grown on top of the magnetic CaB 6. Such results demonstrate the interesting perspective of engineering multifunctional heterostructures by coupling the surface magnetic layer with the diversity of other hexaboride materials.
Authors:
ORCiD logo [1] ;  [2] ;  [1] ;  [2]
  1. West Virginia Univ., Morgantown, WV (United States)
  2. Univ. of Wisconsin, Madison, WI (United States)
Publication Date:
Grant/Contract Number:
SC0010399; SC-0010399
Type:
Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 110; Journal Issue: 10; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics (AIP)
Research Org:
West Virginia Univ., Morgantown, WV (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1466023
Alternate Identifier(s):
OSTI ID: 1349381

Cen, Cheng, Ma, Yanjun, Wang, Qiang, and Eom, Chang -Beom. Surface magnetism and proximity effects in hexaboride thin films. United States: N. p., Web. doi:10.1063/1.4978433.
Cen, Cheng, Ma, Yanjun, Wang, Qiang, & Eom, Chang -Beom. Surface magnetism and proximity effects in hexaboride thin films. United States. doi:10.1063/1.4978433.
Cen, Cheng, Ma, Yanjun, Wang, Qiang, and Eom, Chang -Beom. 2017. "Surface magnetism and proximity effects in hexaboride thin films". United States. doi:10.1063/1.4978433. https://www.osti.gov/servlets/purl/1466023.
@article{osti_1466023,
title = {Surface magnetism and proximity effects in hexaboride thin films},
author = {Cen, Cheng and Ma, Yanjun and Wang, Qiang and Eom, Chang -Beom},
abstractNote = {Here, 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.},
doi = {10.1063/1.4978433},
journal = {Applied Physics Letters},
number = 10,
volume = 110,
place = {United States},
year = {2017},
month = {3}
}