Jump to main content
Jump to site search

Issue 41, 2018
Previous Article Next Article

Magnetic studies of layer-by-layer assembled polyvinyl alcohol/iron oxide nanofilms

Author affiliations


This study reports on investigation of the magnetic properties of layer-by-layer (LbL) assembled nanofilms comprising polyvinyl alcohol (PVA) and citrate-coated magnetite (cit-MAG) nanoparticles deposited onto silicon (SF sample) and glass (GF sample) substrates. DC magnetization measurements were performed over the temperature range of 4 K to 300 K, in the applied magnetic field range of ±60 kOe. The magnetic data of the as-synthesized cit-MAG nanoparticles (F sample) are also collected for comparison. The three as-fabricated samples reveal perfect superparamagnetic (SPM) behavior only around room temperature; at temperatures lower than 200 K the SPM scaling is not observed and all samples behave as interacting superparamagnetic (ISPM) materials. The evolution from the ISPM to the SPM regime is marked by a steady decrease in the hysteretic properties of all samples, with the temperature-dependence of the coercivity decreasing slower than the T1/2 behavior predicted for non-interacting superparamagnetic particles. The modified Bloch's law used to assess information on nanoparticles’ surface spins gives the Bloch's exponent close to 2 (for the F and SF samples) and close to 1 (for the GF sample). Interestingly, the surface spin freezing temperature (Tf) is 8 ± 1 K for all samples. The magnetic behavior of all three samples can be described within the model picture of a core–shell structure for the cit-MAG nanoparticles; the core comprising magnetically-ordered spins whereas the shell behaving as a spin-glass-like system. However, the contribution of the shell magnetism to the effective magnetic properties is much more evident in the GF sample in which magnetic dipole–dipole interaction is three-times weaker than in the SF sample and two times weaker than in the F sample. In contrast, the strong magnetic dipole–dipole interaction in the SF sample affects the surface spins, hindering the onset of magnetically-ordered regions in the nanoparticle's shell, making the surface magnetism contribution negligible. The LbL-fabricated nanofilms herein reported and the presented analysis of their magnetic properties we envisage can support the engineering of magnetic nanofilms for multiple applications.

Graphical abstract: Magnetic studies of layer-by-layer assembled polyvinyl alcohol/iron oxide nanofilms

Back to tab navigation

Publication details

The article was received on 24 Aug 2018, accepted on 28 Sep 2018 and first published on 28 Sep 2018

Article type: Paper
DOI: 10.1039/C8CP05404E
Citation: Phys. Chem. Chem. Phys., 2018,20, 26696-26709

  •   Request permissions

    Magnetic studies of layer-by-layer assembled polyvinyl alcohol/iron oxide nanofilms

    E. Mosiniewicz-Szablewska, A. R. Clavijo, A. P. O. R. Castilho, L. G. Paterno, M. A. Pereira-da-Silva, J. Więckowski, M. A. G. Soler and P. C. Morais, Phys. Chem. Chem. Phys., 2018, 20, 26696
    DOI: 10.1039/C8CP05404E

Search articles by author