Dimensionality tuning of the electronic structure in Fe3Ga4 magnetic materials

Abstract

This work reports on the dimensionality effects on the magnetic behavior of Fe3Ga4 compounds by means of magnetic susceptibility, electrical resistivity, and specific heat measurements. Our results show that reducing the Fe3Ga4 dimensionality, via nanowire shape, intriguingly modifies its electronic structure. In particular, the bulk system exhibits two transitions, a ferromagnetic (FM) transition temperature at T1 = 50 K and an antiferromagnetic (AFM) one at T2 = 390 K. On the other hand, nanowires shift these transition temperatures, towards higher and lower temperature for T1 and T2, respectively. Moreover, the dimensionality reduction seems to also modify the microscopic nature of the T1 transition. Instead of a FM to AFM transition, as observed in the 3D system, a transition from FM to ferrimagnetic (FERRI) or to coexistence of FM and AFM phases is found for the nanowires. Our results allowed us to propose the magnetic field-temperature phase diagram for Fe3Ga4 in both bulk and nanostructured forms. The interesting microscopic tuning of the magnetic interactions induced by dimensionality in Fe3Ga4 opens a new route to optimize the use of such materials in nanostructured devices.

Low-temperature electronic transport of manganese silicide shell-protected single crystal nanowires for nanoelectronics applications

“…For example, we already observed a transformation of the magnetic order, from AFM to ferrimagnetic or a mixture of ferromagnetic and AFM, in the intermediary temperature region of Fe 3 Ga 4 nanowires of similar diameter. 26 On the other hand, this resistivity contribution modication could explain the smallest nanowire unexpectedly exhibiting the lowest resistivity compared to larger nanowires (see Fig. 4a), especially since it presents the highest residual resistivity and a RRR value less than half than for larger nanowires.…”

“…24 This fabrication technique, which combines the metal ux method with nanoporous alumina templates, has already been successfully employed on the fabrication of several intermetallic nanowires. [24][25][26][27] It is a versatile and user-friendly method that presents a possible high yield of around millions of nanowires per squared millimeters. Here, this one-step nanowire production technique allowed us to reproducibly fabricate high crystalline quality manganese silicide oxide-coated nanowires with length up to several tens of microns.…”

Superconducting Properties in Arrays of Nanostructured β-Gallium

“…The MFNN technique 18 – 20 has been successfully developed to nucleate crystalline nanowires inside the pores of an alumina template. The nanoporous template presents several advantages, such as an excellent pore-size control over large areas and large aspect-ratio pores that exhibit a highly regular spatial pattern.…”

“…Here we report results on a nanostructured array of β -Ga synthesized by a novel method of metallic-flux nanonucleation (MFNN) 18 – 20 . The superconducting properties measured in our samples are interpreted taking into account a type-II-like behavior.…”

Pseudo-monocrystalline properties of cylindrical nanowires confinedly grown by electrodeposition in nanoporous alumina templates

“…Pulsed electrodeposition (PED) is a particularly powerful technique for improving the uniform growth of nanowires, avoiding the formation of large and randomly oriented crystallites. 39 In fact, the formation of single-crystal phase nanowires and nanotubes under certain conditions of synthesis has been reported by several research teams, 12,40,41 and the crystalline properties have been determined by local studies using selected-area electron diffraction (SAED) and, in the case of NWs with diameters smaller than 50 nm, high resolution transmission electron microscopy (HRTEM) techniques were employed. 12,42 These characterization methods have the great advantage to perform local analyses that allow the study of a selected area of an individual NW.…”