title: Magnetic properties in α-MnO₂ doped with alkaline elements.
abstract: α-MnO2 nanotubes were fabricated using a hydrothermal technique. Li, Na and K ions were introduced into MnO2 nanotubes to tailor their magnetic properties. It was found that with a doping concentration lower than 12 at%, the nanotubes showed ferromagnetic-like ordering at low temperature (<50 K), while antiferromagnetic coupling dominated their physical behavior with doping concentrations beyond 12 at%. Such experimental phenomenon was in very good agreement with associated first principle calculations. The ferromagnetic-like ordering originates from the breaking of equivalence between two different Mn-O octahedrals in α-MnO2 due to the filling of alkaline ions in the tunnels. Both small charge transfer and lattice distortion play important roles in the ferromagnetic ordering.
authors.affiliation: School of Materials Science and Engineering, University of New South Wales, Kensington, 2052, NSW, Australia.
authors.forename: Li-Ting
authors.initials: LT
authors.lastname: Tseng
authors.affiliation: School of Material Science and Engineering, Zhejiang University, 310027, China.
authors.forename: Yunhao
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Shanxi Key Laboratory of Degradable Biomedical Materials, School of Chemical Engineering, Northwest University, Xi'an, Shanxi 710069, China.
authors.forename: Hai Ming
authors.initials: HM
authors.lastname: Fan
authors.affiliation: School of Materials Science and Engineering, University of New South Wales, Kensington, 2052, NSW, Australia.
authors.forename: Yiren
authors.initials: Y
authors.lastname: Wang
authors.affiliation: School of Materials Science and Engineering, University of New South Wales, Kensington, 2052, NSW, Australia.
authors.forename: Xi
authors.initials: X
authors.lastname: Luo
authors.affiliation: Institute for Synchrotron Radiation. Karlsruhe Institute of Technology, Karlsruhe, Germany.
authors.forename: Tao
authors.initials: T
authors.lastname: Liu
authors.affiliation: School of Materials Science and Engineering, University of New South Wales, Kensington, 2052, NSW, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Munroe
authors.affiliation: School of Materials Science and Engineering, University of New South Wales, Kensington, 2052, NSW, Australia.
authors.forename: Sean
authors.initials: S
authors.lastname: Li
authors.affiliation: School of Materials Science and Engineering, University of New South Wales, Kensington, 2052, NSW, Australia.
authors.forename: Jiabao
authors.initials: J
authors.lastname: Yi