DCMPMS Seminars

Effect of substitution at transition metal sites in rare earth ternary silicides

by Ms. Rajeswari Roy Chowdhury (Ph.D. Student, Saha Institute of Nuclear Physics, Kolkata)

Tuesday, February 21, 2017 from to (Asia/Kolkata)
at AG80
Description
During last few decades, the intermetallic compounds containing rare earth elements have been a subject of intensive studies because of their intriguing physical properties, which have both fundamental and practical significance. Among several families of this group, RET2X2 (RE = rare earths or actinides, T = transition metals, and X = Si or Ge) crystallizing in ThCr2Si2 type structure represents an interesting class due to its attractive magnetic properties. We have intensively studied substitution effects of rare earth and transition metal sites of RET2X2 (RE = Ce, Pr, Nd; T = Co and X = Si) compounds and its impact on magnetic, magneto-transport and magneto-caloric properties. For the first time, vanadium, an element not known to form ThCr2Si2 type pure compounds, have been used for partial substitution of cobalt in antiferromagnetic compounds PrCo2Si2 and NdCo2Si2 causing lattice expansion and significant modification of magnetic properties. Through systematic variation of V-doping percentage, we have shown that that the antiferromagnetic ground state in the parent compounds gets modified to ferrimagnetic and subsequently to ferromagnetic with higher V doping percentage. Subsequent experimental results prove that non-magnetic V atom results in appearance of magnetic moment in the transition metal layers in these class of compounds resulting in complete modification of ground state. Enhancement of magnetocaloric effect as a result of substitution due to modification of magnetic ground state has been observed. A brief study of nuclear magnetic resonance (NMR) in Ce(Co1-xVx)2Si2 throw more insight into the crystal electric field effect in these compounds. Magneto-transport study in RET2X2 compound has shown to exhibit large value of positive MR.