Year: 2019
Type: article
Abstract: The static magnetization and dynamic susceptibility responses of the cluster system within a Griffiths phase of the magnetocaloric compound ${\mathrm{Tb}}_{5\ensuremath{-}x}{\mathrm{La}}_{x}{\mathrm{Si}}_{2}{\mathrm{Ge}}_{2}$ ($x=0.075$) have been investigated. A novel cluster-glass state within the Griffiths phase is formed at a characteristic freezing temperature where short-range ferromagnetic correlations set in the paramagnetic regime. Ferromagneticlike correlations are built up at around 155 K, which suddenly become frozen at a lower temperature $\ensuremath{\sim}140\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, thus in analogy with a reentrant spin glass behavior. The ac susceptibility near the freezing temperature follows a critical slowing down process characterized by ${\ensuremath{\tau}}_{0}={10}^{\ensuremath{-}13}s$ and dynamic exponents $\mathrm{z}\ensuremath{\nu}\ensuremath{\sim}6$ and $\ensuremath{\beta}\ensuremath{\sim}0.4$, similar to well-known spin glass systems. The nonlinear ac susceptibility analysis shows clearly the existence of a transition associated to the reentrant behavior. The origin of the intermediate cluster-glass phase inside the Griffiths phase is proposed to be the result of a combination of short-ranged RKKY intralayer positive exchange interactions between rare-earth ${\mathrm{Tb}}^{3+}$ ions and antiferromagnetic exchange between adjacent interlayers involving Si and Ge atoms in connection to the ${\mathrm{Tb}}^{3+}$ atoms.
Institutions: Consejo Superior de Investigaciones Científicas, Universidad de Zaragoza, Centro Universitario de la Defensa Zaragoza, Universidad de Cantabria, Universidade do Porto, Instituto de Física de Materiais Avançados, Nanotecnologia e Fotónica, University of Aveiro, Instituto de Nanociencia y Materiales de Aragón
Language: Latvian
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2916396267