「Role of pressure on Critical Behavior of some Perovskite Manganites」
Prof. S. Arumugam 氏

Oct 13, 2015


講演題目: Role of pressure on Critical Behavior of some Perovskite Manganites
講 師 : Prof. S. Arumugam
     Centre for High Pressure Research, School of Physics, Bharathidasan University, India
日 時 : 平成27年10月13日 (火) 16:00-17:00
場 所 : 室蘭工業大学 教育・研究1号館A棟 A322(電気電子系セミナー室)

要 旨 :
The high-pressure technique has been recognized as one of the powerful tools to investigate the physical properties of solids because pressure can vary physical parameters cleanly, not introducing disorder. High pressure, which effectively increases the electron transfer interaction or the one electron band-width, is a powerful tool for investigation of the electronic and magnetic properties of manganites. In this lecture, few results on critical behavior of cubic perovskites under pressure and magnetic field will be discussed. Hydrostatic pressure dependence of the order of phase transition in (Sm0.7Nd0.3)0.52Sr0.48MnO3, La0.4Bi0.3Sr0.3MnO3 and Pr0.6Ca0.4Mn0.96B0.04O3 (B = Co and Cr) systems were analyzed. At ambient pressure, these systems undergo a first-order paramagnetic insulator to ferromagnetic-metallic phase transition. The application of pressure on magnetization of (Sm0.7Nd0.3)0.52Sr0.48MnO3 and La0.4Bi0.3Sr0.3MnO3 systems suppress the first-order paramagnetic to ferromagnetic, and leads the second-order one under 1.21 and 0.91 GPa. Similarly, first-second order crossover takes place, are 2.02 and 2.40 GPa for Co and Cr doped samples respectively. In order to understand the nature of ferromagnetism in second order transition, it is essential to determine the critical values, and the assigning them for existing theoretical models such as mean-field, tricritical, Heisenberg and 3D Heisenberg etc., Here, the estimated values for (Sm0.7Nd0.3)0.52Sr0.48MnO3 and Pr0.6Ca0.4Mn0.96Co0.04O3 are close to the 3D Heisenberg model for the Co doped sample suggesting short-range FM interaction. On the other hand, the estimated values for La0.4Bi0.3Sr0.3MnO3 and Pr0.6Ca0.4Mn0.96Cr0.04O3 are close to the 3D Heisenberg model for the Co doped sample suggesting long-range interaction.

世話人  関根ちひろ
室蘭工業大学情報電子工学系学科 (電話0143-46-5000)

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