Low field magnetoresistance of gadolinium nanowire

Abstract

Magnetization reversal and magnetoresistance behavior of perpendicularly magnetized [Co/Pd]4/Au/[Co/Pd]2 nanowiresWe report low field (l 0 H < 0.2 T) magnetoresistance (MR) studies on a single Gd nanowire patterned from a nano-structured film (average grain size $ 35 nm) by focused ion beam. For comparison, we did similar MR measurements on a polycrystalline sample with large crystallographic grains ($4 lm). It is observed that in the low field region where the MR is due to motion of magnetic domains, the MR in the large grained sample shows a close relation to the characteristic temperature dependent magnetocrystalline anisotropy including a sharp rise in MR at the spin reorientation transition at 235 K. In stark contrast, in the nanowire, the MR shows complete suppression of the above behaviours and it shows predominance of the grain boundary and spin disorder controlling the domain response. V C 2014 AIP Publishing LLC. [http://dx.

Magnetoresistance of polycrystalline gadolinium with varying grain size

“…jDq k j which has been reported in our previous work 15 shows a distinct minimum at T % 183 K close to T * . After the minima, it then rises again showing the broad maxima at T $ 125 K and on further cooling jDq k j decreases.…”

“…In Figure 2, we show the normalized temperature derivatives of the resistivity ð¼ 1 q 0 dq dT Þ as a function of T where the bulk result has been taken from our previous work. 15 For the bulk sample there is a clear change in slope of the 1 q 0 dq dT at T C . This is similar to that observed in single crystal of Gd at T C .…”

“…3 Our previous work showed that the magnetic anisotropy of Gd nanowire has an impact of one dimensional structure. 15 The present investigation reports precision low field MR measurements in polycrystalline Gd with grain sizes varying from few microns down to few tens of nanometers. The MR experiments were carried out at low fields (l 0 H 0.2 T), so that contributions to MR by the magnetic domains can be seen.…”

“…[1][2][3][4][5][6]15 The resurgence in the investigations on magnetic properties of Gd arises from the possibility of utilizing the rather high magnetic moment (and high saturation magnetization) in multilayer thin film applications 7 and also understanding basic physics in a metal with localized moments. Some of the recent magnetic studies focus on nanostructured samples with grain size in the domain of few tens of nm.…”

Controlled nanocrystallinity in Gd nanobowls leads to magnetization of 226 emu/g

“…1 The magnetism of Gd arises from the presence of seven unpaired 4f electrons and magnetocrystalline anisotropy. 2 The magnetic properties of Gd display different characteristics than the standard ferromagnetic 3d metals such as Fe and Co. 2 Contrary to non-localized spins in 3d metals, 4f spins are indirectly coupled via the Ruderman-Kittel-Kasuya-Yosida interaction and strongly localized, 3 which brings unique magnetic behavior to Gd at the nanoscale. In recent years Gd nanoparticles have found uses in magnetocaloric refrigeration, 4 neutron-capture therapy, 5 temperature sensing 6 and MRI.…”