Antisite disorder driven cluster glass state and colossal magnetoresistance in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>MnSb</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Se</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math>
Rahul Kumar, A. Sundaresan
Abstract
Antisite disorder plays a significant role in determining the ground state of a magnetic material. The ternary chalcogenide material ${\mathrm{MnSb}}_{2}{\mathrm{Se}}_{4}$ with $\ensuremath{\sim}26%$ antisite disorder between Mn and Sb sites is known to be an antiferromagnet (${T}_{N}=22.5\phantom{\rule{0.28em}{0ex}}\mathrm{K}$) and a type-II mulitferroic. In this paper, we report the effect of increased antisite disorder ($\ensuremath{\sim}40%$) on the magnetic and electrical transport properties of this compound. Magnetic susceptibility and heat-capacity measurements indicate the absence of long-range magnetic ordering. Furthermore, AC susceptibility measurements unfold its nonequilibrium magnetic dynamics at low temperatures. Data analysis with various dynamic scaling models, namely, power law, Arrhenius law, and Vogel-Fulcher confirm a cluster glass state. Moreover, the presence of magnetic memory effect and magnetic relaxation reveal the nonequilibrium dynamics of the system through many metastable states. In addition, a negative colossal magnetoresistance is observed below the freezing temperature due to competing ferromagnetic and antiferromagnetic interactions induced by increased antisite disorder. These results indicate that ${\mathrm{MnSb}}_{2}{\mathrm{Se}}_{4}$ is a new addition to a very small group of chalcogenides which show negative colossal magnetoresistance.