Absence of long-range Ni∕Mn ordering in ferromagnetic La2NiMnO6 thin films

Abstract

Epitaxial La 2 NiMnO 6 thin films have been grown on (001)-orientated SrTiO 3 using the pulsed laser deposition technique. The thin films samples are semiconducting and ferromagnetic with a Curie temperature close to 270 K, a coercive field of 920 Oe, and a saturation magnetization of 5 µ B per formula unit. Transmission electron microscopy, conducted at room temperature, reveals a majority phase having "I-centered" structure with a ≈ c ≈ a sub 2 and b ≈ 2a sub along with minority phase domains having a "P-type" structure (a sub being the lattice parameter of the cubic perovskite structure). A discussion on the absence of Ni/Mn long-range ordering, in light of recent literature on the ordered double-perovskite La 2 NiMnO 6 is presented.

Multiferroic double perovskites: Opportunities, issues, and challenges

“…It is here important to note these three distinct phases are thermodynamical stable. Also of importance, the short-range ordering can also be induced through oxygen or cation vacancy and thus is very sensitive to the synthesis conditions 5,10 . This outlines the real complexity associated in obtaining a totally ordered phase.…”

Electronic structure and optical band gap of CoFe2O4 thin films

“…The arrangement of transition metal ions in oxide magnetic materials plays a crucial role on its structure as well as on physical properties [1][2][3]. In particular the arrangement of transition metal ions in tetrahedral and/or octahedral sites of spinel structure is very appealing.…”

Stabilization and functional properties of La3NiAlMnO9 and La3CoAlMnO9 magnetoelectric triple perovskites

“…For LNAMO, it is about 3.99 Å. Surprisingly, these artificial oxides show a significant enhancement in their pseudo-cubic lattice parameter compared to their respective LCMO (~ 3.89 Å) and LNMO (~ 3.87 Å) bulk and thin films [6][7][8][9][10][11][12][13][14] . We interpret this counter-intuitive behaviour as an indication that the presence of Al in the crystal structure provokes an expansion of the out-of-plane lattice parameter to minimize the elastic and columbic energy of these polar systems.…”

“…In our recent studies of self-ordered La 2 CoMnO 6 (LCMO) thin films grown by pulsed-laser deposition, we demonstrated that the ordered Co/Mn cations can be obtained only in a limited window of growth parameters 11 . It has been clearly established that the magnetic behaviour of these compounds is a very sensitive probe of the presence of cation ordering [5][6][7][8][9][10][11][12][13][14] . Furthermore, the MnO 6 and CoO 6 layers with Mn 4+ and Co 2+ ions alternating along the (111) crystal axis generate a strong polar character as confirmed by an enhanced dielectric constant 14 and a large magnetodielectric coupling in the vicinity of the magnetic phase transition 7,[14][15] .…”

“…and A = La) represent an alternative avenue to search for such innovative materials [4][5][6][7][8][9][10][11][12][13][14][15] .…”