Prof. S. Arumugam [Bharathidasan University, Tiruchirappalli, INDIA]

Title:     Role of pressure on Critical Behavior of some Perovskite Manganites

Time:     9:00 – 10:00 AM, June 15, 2015, Monday

Place:   Conference room 201, Build 6, HPSTAR (Shanghai)

Host:     Dr. Wenge Yang

Abstract:

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. In this talk, few results on critical behavior of cubic perovskites such as (Sm0.7Nd0.3)0.52Sr0.48MnO3, La0.4Bi0.3Sr0.3MnO3 and Pr0.6Ca0.4Mn0.96B0.04O3 (B = Co and Cr) systems under pressure were analyzed. At ambient pressure, these systems undergo a first-order PI to FM 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 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 during transport measurements. In order to understand the nature of FM in second order transition, it is essential to determine the critical values, and the assigning them for existing theoretical. 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. In conclusion, pressure can also be a tool for phase transition from discontinuous to continuous.

        References:

P. Sarkar, S. Arumguam et al., Phy. Rev. Lett. 103, 057205 (2009)

R. Thiyagarajan, S. Arumugam et al., J. App. Phy. 113 023904 (2013)

Biography of the Speaker:

Prof. S. Arumugam got his Ph.D., degree in Physics from Anna University, Chennai, India in 1993. Then, he joined as Post-doc. University of Tokyo, Japan, and as a full-time Professor in Bharathidasan University, India from 2000. He is established a Centre for High Pressure Research in University Campus on 2008, and he is the Coordinator of the same Centre. He group is currently focusing on various strongly correlated systems under pressure, magnetic field and low temperature.