Fe 3 − x Zn x O 4 thin film as tunable high Curie temperature ferromagnetic semiconductor

Abstract

Epitaxial ferri(ferro)magnetic Fe3−xZnxO4 thin films (x=0–0.9) were prepared using a pulsed-laser deposition technique. The electrical conductivity and magnetic properties of Fe3−xZnxO4 thin film were systematically modulated for the entire range of Zn substitution. Anomalous Hall coefficient measurements revealed the presence of spin-polarized carriers at room temperature. Valence band spectra obtained by hard x-ray photoemission spectroscopy revealed that the density of states near the Fermi level was reduced with an increasing Zn concentration of x. These results indicate that this system will serve as a tunable ferromagnetic semiconductor with a strong electron correlation.

EpitaxialZnxFe3−xO4thin films: A spintronic material with tunable electrical and magnetic properties

“…This is in perfect agreement with our observation and literature data 12,13 . We note however, that the increase of resistivity is not only caused by a reduction of the carrier density but also by several other effects.…”

“…The c axis parameter increases from a value below (x = 0, tensile strain) to a value above the bulk value (x 0.3, compressive strain). The expansion of the out-of-plane lattice parameter with increasing x has been reported also for (111)-oriented films grown on Al 2 O 3 (0001) substrates 12 . However, we note that those films are relaxed due to the very large lattice mismatch of 8% between film and substrate.…”

“…Second, as done in our work, Fe spinel structure 21 . Again some of the antiferromagnetically coupled moments on the A sites are removed, leading to an initial increase of the saturation magnetization at low Zn substitution 12,22 . However, in the same way as discussed before, a finite Yafet-Kittel angle and, in turn, a reduction of the saturation magnetization is expected going to larger substitution levels 22 .…”

“…First, it has both a high Curie temperature of T C ≃ 860 K and according to band structure calculations is expected a half-metal 9 corroborated by spin-resolved photoelectron spectroscopy 10,11 . Second, recent experiments indicated that both the electronic and magnetic properties of Fe 3 O 4 thin films can be nicely tailored in solid solution systems of Fe 3−x M x O 4 (M = Zn, Mn) 12,13 . Third, it has been demonstrated that the magnetic anisotropy of Fe 3 O 4 can be tuned by elastic stress imposed by a piezoelectric actuator 14 .…”

Anomalous Hall effect in ZnxFe3-xO4: Universal scaling law and electron localization below the Verwey transition

“…The zinc-substituted Fe 3 O 4 oxide, namely Zn x Fe 3-x O 4 , has been much less investigated although it offers the possibility to tune the magnetic or electrical properties as a function of the Zn content, while maintaining the essential physical specificities of magnetite. [12][13][14][15][16][17] The Hall effect in ferromagnetic compounds has by its own been the subject of intense research (for a review see Ref. 18).…”