Critical behavior and magnetic entropy change in Nd_0.7Sr_0.1Ba_0.1Ca_0.1MnO_3−δ perovskite manganite

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• 作者：N. Mtiraoui^a ; M. Chennabasappa^b ; R. Decourt^b ; O. Toulemonde^b ; J. Dhahri^c ; M. Oumezine^a ; ^{mtiraoui_naima@yahoo.fr" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Critical exponent ; Phase transition ; Manganites
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：January 2016
• 年：2016
• 卷：42
• 期：1
• 页码：1036-1043
• 全文大小：1368 K

文摘

The aim of our study was to investigate the critical exponents of Nd_0.7Sr_0.1Ba_0.1Ca_0.1MnO_3−δ material around its paramagnetic to ferromagnetic phase transition. Reliable critical exponents i.e. β=0.355, γ=1.329, and δ=4.867 at the critical temperature T_C=117 K were refined using modified Arrott plot and Kouvel–Fisher methods. The critical exponent δ=4.760±0.129 was further separately determined from the isothermal magnetization data. Finally these critical exponents fulfill the Widom scaling relation δ=1+γ/β. Based on these analysis, the magnetization–field–temperature (M–H–T) data around T_C collapses into two independent curves obeying the single scaling equation M(H,ε)=|ε|^βf_±(H/|ε|^β+γ), with ε=(T−T_C)/T_C is the reduced temperature. Once again, the critical exponents are confirmed by the field dependence of the magnetic entropy change relation ∆S_M|_T=TC ∞Hⁿ with n=1+(β−1)/(β+1). The obtained critical exponents for Nd_0.7Sr_0.1Ba_0.1Ca_0.1MnO_3−δ manganite are in accordance with the prediction of the 3D-Heisenberg model with short-range magnetic interactions. The temperature dependence of specific heat and magnetic entropy change ΔS_M further supports second order PM–FM phase transition and shed light the A-site-disordered perovskite effect on the magnetocaloric properties.