Enhanced Low-field Magnetoresistance of La_0.7Sr_0.3Mn_1+dO₃-Mn₃O₄Composite Films Prepared by ex-situ Solid Phase Crystallization

Abstract

We report improved low-field magnetoresistance (LFMR) effects of the La 0.7 Sr 0.3 Mn 1+d O 3 -Mn 3 O 4 composite films with the nominal composition of La 0.7 Sr 0.3 MnO 3 (LSMO)-50 mol% Mn 3 O 4 . The composite films were fabricated by ex-situ solid phase crystallization (SPC) of amorphous films at the annealing temperature region of 900-1100 o C for 2 h in a pure oxygen atmosphere. The amorphous films were deposited on polycrystalline BaZrO 3 (poly-BZO) substrates by dc-magnetron sputtering at room temperature. The Curie temperatures (T C ) of all composite films were insignificantly altered in the range of 368-372 K. The highest LFMR value of 1.29 % in 0.5 kOe with the maximum dMR/dH value of 37.4%kOe −1 at 300 K was obtained from 900 nm-thick composite film annealed at 1100 o C. The improved LFMR properties of the composite films are attributed to effective spin-dependent scattering at the La 0.7 Sr 0.3 Mn 1+d O 3 grain boundaries sharpened by adjacent chemically compatible Mn 3 O 4 grains.

Magneto-transport properties of La0.7Sr0.3MnO3–manganese oxide composite films on YSZ substrates prepared using aerosol deposition

“…In particular, in the field region of 10-30 Oe, the annealed composite films exhibit (dMR/dH) max values larger than 100%kOe À 1 which are unprecedentedly high compared with those reported for pure manganite or LSMO-based composite samples [14,22,30]. According to previous reports, the (dMR/dH) max value of 28.3%kOe À 1 was achieved at 300 K in the field region of 10-30 Oe from the LSMM composite bulk sample with the same composition [14], 37.4%kOe À 1 at 300 K in the field range of 10-30 Oe from a 0.9 μm-thick LSMO-50 mol% Mn 3 O 4 composite film deposited by dc sputtering [22], and $ 12%kOe À 1 and $ 20% kOe À 1 at room temperature in the field range of 10-30 Oe from La 0.67 Sr 0.33 MnO 3 and La 0.67 Ba 0.33 MnO 3 bulk samples, respectively [30]. Therefore, among these materials the annealed LSMM composite film is the most promising for real applications since a MR sensor should be operated under very low field (o several tens of Oersted) at room temperature.…”

“…Many groups [13][14][15][16][17][18] have attempted to produce a composite sample between pure LSMO and a secondary phase, and successfully enhanced the LFMR effect by modifying the grain boundary region of LSMO into a more effective spinscattering center. For example, the LFMR effect has been improved by preparing LSMO-insulating oxide composite films using various methods, including pulsed laser deposition (PLD) [19][20][21], magnetron sputtering [22], and metal-organic decomposition (MOD) [23,24]. The reported LFMR values of the composite films, however, remain inadequate for real applications because the values are less than 1% at room temperature.…”

Flexible La0.67Sr0.33MnO3:ZnO Nanocomposite Thin Films Integrated on Mica

“…Owing to the novel physical properties and potential applications in advanced electronic and spintronic devices, perovskite manganite with the generic formula of RE 1−x AE x MnO 3 (RE = rare earth, AE = Ca, Sr, Ba, and Pb) has attracted intensive research interests (Wang et al, 2014;Zheng et al, 2019).The strong coupling of spin, charge, orbital, and lattice degrees of freedom results in exotic magnetic and transport properties in perovskite manganite (Zhang et al, 2022;Moshnyaga et al, 2003). For example, colossal magnetoresistance (CMR) has been achieved in doped perovskite manganite, despite the fact that a high magnetic field (several Tesla) is required, which limits its further application (Kang et al, 2012;Wang et al, 2016). Therefore, extensive research efforts have been devoted to exploring magnetoresistance (MR) under low field, termed low-field magnetoresistance (LFMR).…”