Two-dimensional growth, anisotropic polaron transport, and magnetic phase segregation in epitaxial Nd0.52Sr0.48MnO3 films

Abstract

͑Submitted May 5, 2010͒ Fiz. Nizk. Temp. 37, 141-149 ͑February 2011͒ Nd 0.52 Sr 0.48 MnO 3 films have been fabricated by dc magnetron sputtering on single-crystal LaAlO 3 ͑001͒ and SrTiO 3 ͑011͒ substrates with additional annealing to relax the lattice strain. Although the Nd 0.52 Sr 0.48 MnO 3 films were deposited simultaneously on different substrates at the same deposition rate, they differ in thickness by a factor of Ӎ ͱ 2. The observed difference in thickness is explained by the two-dimensional ͑layer-by-layer͒ film growth, rather than by a difference in growth rate controlled by the crystalline orientation of the substrate. An analysis of optical and transport properties reveals that the observed anisotropy in the polaron motion is governed by a strong anisotropy in the trapping energy, rather than in polaron formation. It is shown that the deposited Nd 0.52 Sr 0.48 MnO 3 films exhibit magnetic behavior typical of two-phase magnetic systems and should be regarded as an assembly of interacting magnetic clusters.

Irreversibility and anisotropy of the low-temperature magnetization in manganites. Spin-glass polyamorphism

“…It also contains the references from which the data were obtained. 17,[20][21][22]38,40,[43][44][45] It should be noted that Fig. 5 (as well as Fig.…”

“…The temperature dependence of the magnetization of segregated perovskites in a constant magnetic field at different cooling conditions, in a fixed magnetic field (field cooled, FC) and in zero field (zero field cooled, ZFC) has been the subject of a particularly detailed study. It turns out [12][13][14][15][16][17][18][19][20][21][22][23] that the temperature dependences of the magnetization measured under ZFC and FC conditions coincide only at temperatures above a certain temperature T * , which depends on the magnetic field H. Below this temperature they "split." This observation is consistent with the peculiarities of the magnetic phase T-H diagrams of manganites with colossal negative magnetoresistance (CMR).…”

Origin of an enhanced colossal magnetoresistance effect in epitaxial Nd0.52Sr0.48MnO3 thin films

“…Therefore, the experimental observation of a such enhanced CMR effect is more expected in the manganites with , N C T T where N T is the Néel temperature. The Nd 0.52 Sr 0.48 MnO 3 thin film is a more suitable object for a check on this theoretical approach, because manifests a presence of the FM and AFM phases, the transition temperature of which can be controlled by the deposition mode [3]. Moreover, it was shown that both phases are formed from the paramagnetic state and exist separately to each other.…”

Magnetic proximity effect in Pr0.5Ca0.5MnO3/La0.7Sr0.3MnO3 bilayered films

“…Two different approaches are employed for a description of the magnetic properties for manganites in the phase-separated state. There are the modified classical spin-glass theory [14,43] and the model of the superparamagnetic (SPM) clusters with a strong dipolar interaction [38][39][40][41][42]. Figure 10,b presents the magnetic-field dependences of * , T which was evaluated as a peak position on the ZFC ( ) M T curve, for …”

“…which was obtained in the framework of model for the interacting SPM clusters [38]. Here β 3 T -1 is a certain coefficient between the saturation magnetic moment and an applied magnetic field.…”