Year: 2018
Type: article
Abstract: We report the structural, static, and dynamic properties of ${\mathrm{Cr}}_{0.5}{\mathrm{Fe}}_{0.5}\mathrm{Ga}$ by means of powder x-ray diffraction, dc magnetization, heat capacity, ac susceptibility, magnetic relaxation, and magnetic memory effect measurements. The dc magnetization and ac susceptibility studies reveal a spin-glass transition at around ${T}_{\mathrm{f}}\ensuremath{\simeq}22$ K. An intermediate value of the relative shift in freezing temperature $\ensuremath{\delta}{T}_{\mathrm{f}}\ensuremath{\simeq}0.017$, obtained from the ac susceptibility data reflects the formation of cluster spin-glass states. The frequency dependence of ${T}_{\mathrm{f}}$ is also analyzed within the framework of dynamic scaling laws such as power law and Vogel-Fulcher law. The analysis using power law yields a characteristic time constant for a single spin flip $\ensuremath{\tau}*\ensuremath{\simeq}1.1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ s and critical exponent $z{\ensuremath{\nu}}^{\ensuremath{'}}=4.2\ifmmode\pm\else\textpm\fi{}0.2$. On the other hand, the Vogel-Fulcher law yields the characteristic time constant for a single spin flip ${\ensuremath{\tau}}_{0}\ensuremath{\simeq}6.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$ s, Vogel-Fulcher temperature ${T}_{0}=21.1\ifmmode\pm\else\textpm\fi{}0.1$ K, and an activation energy ${E}_{\mathrm{a}}/{k}_{\mathrm{B}}\ensuremath{\simeq}16$ K. The value of $\ensuremath{\tau}*$ and ${\ensuremath{\tau}}_{0}$ along with a nonzero value of ${T}_{0}$ provide further evidence for the cluster spin-glass behavior. The magnetic field dependent ${T}_{\mathrm{f}}$ follows the de Almeida-Thouless (AT) line with a non-mean-field type instability, reflecting either a different universality class or strong anisotropy in the spin system. A detailed nonequilibrium dynamics study via relaxation and memory effect experiments demonstrates the evolution of the system through a number of intermediate metastable states and striking memory effects. All the above observations render a cluster spin-glass behavior in ${\mathrm{Cr}}_{0.5}{\mathrm{Fe}}_{0.5}\mathrm{Ga},$ which is triggered by magnetic frustration due to competing antiferromagnetic and ferromagnetic interactions and magnetic site disorder. Moreover, the asymmetric response of magnetic relaxation with respect to the change in temperature, below the freezing temperature can be explained by the hierarchical model.
Authors: Pallab Bag, P. R. Baral, R. Nath
Language: Latvian
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Award: G6130499100
OpenAlex ID: W2897130233