Turning antiferromagnetic Sm_0.34Sr_0.66MnO₃ into a 140 K ferromagnet using a nanocomposite strain tuning approach

Abstract

Ferromagnetic insulating thin films of Sm(0.34)Sr(0.66)MnO3 (SSMO) on (001) SrTiO3 substrates with a T(C) of 140 K were formed in self-assembled epitaxial nanocomposite thin films. High T(C) ferromagnetism was enabled through vertical epitaxy of the SSMO matrix with embedded, stiff, ∼40 nm Sm2O3 nanopillars giving a c/a ratio close to 1 in the SSMO. In contrast, bulk and single phase SSMO films of the same composition have much stronger tetragonal distortion, the bulk having c/a >1 and the films having c/a <1, both of which give rise to antiferromagnetic coupling. The work demonstrates a unique and simple route to creating ferromagnetic insulators for spintronics applications where currently available ferromagnetic insulators are either hard to grow and/or have very low T(C).

Strain-tuned enhancement of ferromagnetic TC to 176 K in Sm-doped BiMnO3 thin films and determination of magnetic phase diagram

“…For c/a  > 0.99, hidden AFM is obtained and is manifest as a tail behaviour in the M  −  T curves. The strong relationship between magnetic structure and c/a is consistent with other manganites262930313233. For example, for La 0.5 Sr 0.5 MnO 3 , by varying the c/a ratio from 0.97 to 1.06, the magnetic phase changes from A-type AFM to FM to C-type AFM29.…”

Research Update: Fast and tunable nanoionics in vertically aligned nanostructured films

“…Although this review might not cover all findings in this research field, we hope that it will help the readers to quickly jump into the field of ionic devices based on VAN films. If the readers are interested in other applications, such as electric and magnetic properties of VAN films, there are several reviews [54][55][56] and reports [57][58][59][60][61][62][63][64][65][66][67][68][69] which are worth reading.…”

Achieving ferromagnetic insulating properties in La0.9Ba0.1MnO3 thin films through nanoengineering

“…10 However, bulk FMI properties are modified or vanished and cannot be translated to thin films, [11][12][13] and an anomalous metallic behaviour is observed with an insulator-to-metal (I-M) transition at a wide range of temperatures depending on the growth and heat treatment process. Indeed, the lack of ability to translate bulk properties to thin films is well-known in the broad range of manganite compositions, 14,15 and indeed in many other functional perovskites (including ferroelectrics and superconductors). 16,17 A key reason for the thin film anomalies is the strong coupling between the charge, orbital and spin degrees of freedom, 18 making the properties highly tunable by chemical and physical pressure.…”

“…While the matrix phase is initially clamped by the substrate ip, after a certain thickness the columns dominate the strain state of the matrix phase 32 both along the ip and op directions. 15,33 The columns act as "anchors" to maintain a stable and uniform strain state of the matrix, without inhomogeneity or relaxation, and without thickness limitation. 34 3.…”

“…Overall, the resulting 3D strain control is totally different to what is achievable in a plain film (PF). 15,35 4. The vertical strain state can be easily controlled by changing growth conditions, phase ratio and film thickness, and the nanocolumn phase enables a uniform strain to be maintained even when the film is very thick.…”