Exchange Bias Effect and Magnetic Properties in ${\hbox{La}}_{0.7}{\hbox{Sr}}_{0.3}{\hbox{MnO}}_{3}\hbox{-}{\hbox{NiO}}$ Nanocomposite Films

Abstract

The magnetic exchange coupling effect has been investigated in La Sr MnO (LSMO)-NiO nanocomposite films prepared by pulsed laser deposition on SrTiO (001) and (110) single crystal substrates. The films show an enhanced coercivity field Oe compared with the same thickness single pure LSMO thin film. The composite films exhibit a large exchange bias field Oe after applying a 4000 Oe field cooling. The values of the exchange bias field decrease with increasing temperature and become zero at about 45 K, which corresponds to the conventional exchange bias blocking temperature ( ), regardless of epitaxial growth directions on (001) or (110) SrTiO substrates. We speculate that there may be magnetic interaction at the NiO and LSMO boundaries or charge transfer between the Ni and Mn ions, resulting in the formation of ferromagnetic interaction at the interface. The Curie temperature decreased from 340 K of the LSMO single film to 200 K of the nanocomposite film. The results demonstrate that the magnetic state of the composite film is directly related to the Mn-O-Mn and Mn-O-Ni spin interaction energy. In addition to this, the Mn-O-Ni at the boundary may also form the magnetic region that pins the ferromagnetic LSMO phase. Index Terms-Exchange bias (EB), magnetic transport properties, pulse laser deposition (PLD).

Evolution of microstructure, strain and physical properties in oxide nanocomposite films

“…Artificially constructed horizontal oxide heterointerfaces in the form of superlattices, multilayers, and/or heterostructures have been widely investigated to manipulate physical properties789. Recently, nanocomposites with a vertical interface network are emerging as an alternative approach to tune physical properties since microstructure, interfacial coupling, and lattice strain can be tailored from 2D to 3D10111213141516171819. The lack of substrate clamping effect and the presence of large interfacial area in thick vertically aligned nanocomposite films in comparison with conventional horizontal heterostructures make such a new 3D architecture attractive20 to tune the functionalities of materials21.…”

Strong perpendicular exchange bias in epitaxial La0.7Sr0.3MnO3:LaFeO3 nanocomposite thin films

“…Previous reports suggest that larger strain in LSMO or LFO and smaller interfacial strain can lead to stronger spin frustration in the system. 28,30,31,41 As summarized in Table I, it can be expected that sample of x = 0.33 and 0.67 exhibit stronger spin frustration than that of x = 0.5, due to the large LFO strain (−1.16%) and small interfacial strain (0.025%) for x = 0.33, and large LSMO strain (1.3%) together with 0.24% interfacial strain for x = 0.67. While sample of x = 0.5 has a small strain for both LSMO (0.64%) and LFO (−0.76%) and a larger interfacial strain (0.38%), making both LSMO FM and LFO AFM state stable and a weak spin frustration across the interface.…”