Magnetic RE<sub>2</sub>NiMnO<sub>6 </sub>double-perovskites: thin films and superlattices
ORAL · Invited
Abstract
The double-perovskite RE2NiMnO6 (RE= rare earth) family is characterized for being insulating ferromagnets, an unusual combination of properties. Ferromagnetism arises through oxygen-mediated superexchange in the rock salt-ordered Ni/Mn sublattice. The Curie Temperature of La2NiMnO6 is Tc=280K, and for the other members of the family Tc decreases linearly with the size of the ionic radius of the RE [1].
Here we will show that epitaxial RE2NiMnO6 films (RE=La, Nd, Sm), grown by off-axis RHEED magnetron sputtering, display long-range Ni2+ and Mn4+ order and strain-independent bulk-like TC at a thickness of 30 unit cells [2,3]. We find that the ferromagnetic behavior occurs down to ultra-low thicknesses of (at least) 3 unit cells (~1.2 nm). However, below 10 unit cells, the magnetic properties deteriorate due to an interfacial charge transfer caused by the polar discontinuity at the RE2NiMnO6/SrTiO3 interface [3,4]. For the case of Nd2NiMnO6, a detailed x-ray magnetic circular dichroism (XMCD) study allows us to separate the magnetic components into a robust ferromagnetic Ni/Mn sublattice and a paramagnetic Nd sublattice [3].
We will also present our latest efforts in combining different RE2NiMnO6 double perovskites into potential multiferroic artificially-layered superlattices as predicted by first principles [5].
Here we will show that epitaxial RE2NiMnO6 films (RE=La, Nd, Sm), grown by off-axis RHEED magnetron sputtering, display long-range Ni2+ and Mn4+ order and strain-independent bulk-like TC at a thickness of 30 unit cells [2,3]. We find that the ferromagnetic behavior occurs down to ultra-low thicknesses of (at least) 3 unit cells (~1.2 nm). However, below 10 unit cells, the magnetic properties deteriorate due to an interfacial charge transfer caused by the polar discontinuity at the RE2NiMnO6/SrTiO3 interface [3,4]. For the case of Nd2NiMnO6, a detailed x-ray magnetic circular dichroism (XMCD) study allows us to separate the magnetic components into a robust ferromagnetic Ni/Mn sublattice and a paramagnetic Nd sublattice [3].
We will also present our latest efforts in combining different RE2NiMnO6 double perovskites into potential multiferroic artificially-layered superlattices as predicted by first principles [5].
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Publication: [1] R. Booth et al., Materials Research Bulletin 44, 1559 (2009).
[2] G. De Luca et al., APL Materials 9, 081111 (2021).
[3] J. Spring et al., Physical Review Materials (in press).
[4] G. De Luca et al, Advanced Materials 34, 2203071 (2022).
[5] H. J. Zhao et al., Nature Communications 5, 4021 (2014).
Presenters
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Marta Gibert
- TU Wien
- Solid State Physics Institute, TU Wien