Observation of spin-glass behavior in nickel adsorbed few layer graphene

Journal of Applied Physics (Impact Factor: 2.18). 04/2012; 113(2). DOI: 10.1063/1.4774062
Source: arXiv


Nickel-adsorbed graphene was prepared by first synthesizing graphite oxide
(GO) by modified Hummers' method and then reducing a solution containing both
GO and $Ni^{2+}$. EDX analysis showed 31 atomic percent nickel was present.
Magnetization measurements under both dc and ac magnetic fields were carried
out in the temperature range 2 K to 300 K. The zero field cooled and field
cooled magnetization data showed a pronounced irreversibility at a temperature
around 20 K. The analysis of the ac susceptibility data were carried out by
both Vogel-Fulcher as well as power law. From dynamic scaling analysis the
microscopic flipping time $\tau_{0}\sim 10^{-13} s$ and critical exponent
$z\nu=5.9\pm0.1$ were found, indicating presence of conventional spin glass in
the system. The spin glass transition temperature was estimated as 19.5 K.
Decay of thermoremanent magnetization (TRM) was explained by stretched
exponential function with a value of the exponent as 0.6 .
From the results it is concluded that nickel adsorbed graphene behaves like a

Download full-text


Available from: Sreemanta Mitra
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this work, the magnetic properties of the ferromagnetic and antiferromagnetic two layer spin-1/2 Ising nanographene systems are investigated within the effective field theory. We find that the magnetizations and the hysteresis behaviors of the central graphene atoms are similar to those of the edge graphene atoms in the ferromagnetic case. But, they are quite different in the antiferromagnetic case. The antiferromagnetic central graphene atoms exhibit type II superconductivity and they have triple hysteresis loop. The peak effect (PE) region is observed on the hysteresis curves of the antiferromagnetic Ising nanographene system. Therefore, we suggest that there is a strong relationship between the antiferromagnetism and the peak effect. Our results are in agreement with some experimental works in recent literature.
    Full-text · Article · Nov 2014 · Physica B Condensed Matter
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The clear understanding of exchange interactions between magnetic ions in substituted BiFeO3 is the prerequisite for the comprehensive studies on magnetic properties. BiFe0.5Mn0.5O3 films and BiFeO3/BiMnO3 superlattices have been fabricated by pulsed laser deposition on (001) SrTiO3 substrates. Using piezoresponse force microscopy (PFM), the ferroelectricity at room temperature has been inferred from the observation of PFM hysteresis loops and electrical writing of ferroelectric domains for both samples. Spin glass behavior has been observed in both samples by temperature dependent magnetization curves and decay of thermo-remnant magnetization with time. The magnetic ordering has been studied by X-ray magnetic circular dichroism measurements, and Fe-O-Mn interaction has been confirmed to be antiferromagnetic (AF). The observed spin glass in BiFe0.5Mn0.5O3 films has been attributed to cluster spin glass due to Mn-rich ferromagnetic (FM) clusters in AF matrix, while spin glass in BiFeO3/BiMnO3 superlattices is due to competition between AF Fe-O-Fe, AF Fe-O-Mn and FM Mn-O-Mn interactions in the well ordered square lattice with two Fe ions in BiFeO3 layer and two Mn ions in BiMnO3 layer at interfaces.
    Full-text · Article · Mar 2015 · Scientific Reports
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The effects of the distance between two nearest-neighbor layers on the magnetization and hysteresis properties (remanence, coercivity and loop area) of the ferromagnetic trilayer Ising nanostructure (TLINS) with ABA stacking sequence are investigated by using Kaneyoshi approach (KA) within the effective field theory. We find that the ferromagnetic properties of the TLINS strongly depend on distance between the layers. The layers have strong interactions at a certain minimum distance and they have no interactions at a certain maximum distance . Hence, we suggest an effective distance at for the TLINS. It is observed that the critical temperature sharply increases as the distance decreases at slowly increases as the distance decreases at and has a certain constant value at . The critical field points fastly increase as the distance decreases and has different value for the central and edge atoms at , slowly increases as the distance decreases at and is same value for the central and edge atoms at and has a certain constant value at . Since the distance has no effect on the critical temperature and critical field points of the TLINS and they have a constant value at , the TLINS behaves as a single layer Ising nanostructure (SLINS) at high distances.
    Full-text · Article · Apr 2015 · Physica A: Statistical Mechanics and its Applications
Show more