A Short Review on Verwey Transition in Nanostructured Fe₃O₄ Materials

Abstract

Verwey transition (VT) of Fe3O4 has been extensively investigated as this results in sharp changes in its physical properties. Exploitation of VT for potential applications in spin/charge transport, multiferroicity, exchange bias, and spin Seebeck effect-based devices has attracted researchers recently. Although hundreds of reports have been published, the origin of VT is still debatable. Besides, not only the size effects have a significant impact on VT in Fe3O4, even the conditions of synthesis of Fe3O4 nanostructures mostly affect the changes in VT. Here, we review not only the effects of scaling but also the growth conditions of the Fe3O4 nanostructures on the VT and their novel applications in spintronics and nanotechnology.

Observation of Cluster Glass and Griffiths‐like Phase in Fe3O4Nanostructures

“…Therefore, all the Fe 2+ cations only contribute to the magnetic moment, resulting in a net spin only magnetic moment of 4 μ B . [ 3 ]…”

“…In contrast, octahedral “B” positions are equally occupied by Fe 3+ and Fe 2+ cations, and that can be represented by Fe 3+ Td [Fe 2+ Oh , Fe 3+ Oh ]O 4 . [ 3 ] Hence, there is a mixed valence of Fe on the octahedral sublattice where electrons can hop between Fe 2+ and Fe 3+ states giving rise to semi‐metallic nature.…”

“…[ 4 ] VT provides information to understand the crystal lattice and electronic structure of Fe 3 O 4 and is vital for its potential applications in nanoelectronics and spintronics. [ 3 ] Upon cooling through VT temperature T V , the lattice distorts from a cubic to monoclinic structure. [ 5 ] Also, in the low‐temperature phase, Fe 3 O 4 is an insulator; hence, T V is identical to its metal–insulator transition, as well.…”

Unveiling the role of Fe3O4 in polymer spin valve near Verwey transition

“…Meanwhile, the selection of FM electrode has been a common approach to optimize the band alignment and further improve the device performance. Compared with conventional FM electrodes such as La0.67Sr0.33MnO3 (LSMO), Co, Fe, NiFe, etc., Fe3O4 has advantages of high Curie temperature (Tc = 858 K), half-metallic nature with theoretical 100% spin polarization, moderate conductivity that partially solved the problem of conductivity mismatch with organic semiconductor, and anti-oxidative property at the same time [25][26][27], which is desirable for the construction of room-temperature OSV devices [28][29][30]. Moreover, a first-order metal-insulator phase transition (Tv ≈ 122 K) associated with the changes in crystal lattice and energy band structure, well-known as Verwey transition [27,31], makes Fe3O4 electrode attractive for spindependent interfacial modification in OSV devices [32].…”

“…Though the physical properties of Fe3O4 have been widely studied [27,33,34], there is little discussion about its role in OSV. The magnetoresistance (MR) in Fe3O4 film arisen from antiphase boundaries (APBs) usually has a distinct temperature dependence [35,36], and such intrinsic interference from FM electrode itself will cause an overestimation of effective spin signal in OSVs [37].…”