On the synthesis and characterization of a new manganite type CMR material: La0.7Hg0.3MnO3 |
| |
Authors: | P K Siwach H K Singh N Khare A K Singh O N Srivastava |
| |
Affiliation: | a Department of Physics, Banaras Hindu University, Varanasi 221005, India b National Physical Laboratory, Dr. K.S. Krishnan Road, New Delhi 110012, India |
| |
Abstract: | A new manganite type CMR material, La0.7Hg0.3MnO3 has been successfully synthesized and has been found to exhibit magnetoresistance (≈9%) at low fields (≈1.5 kG). The synthesis has been carried out through a solid state reaction route consisting of the formation of La0.7MnO3 followed by diffusion of Hg leading to La0.7Hg0.3MnO3. The as grown samples are polycrystalline and correspond to an orthorhombic unit cell with the lattice parameters; a=5.5183 Å, b=5.6383 Å and c=7.5368 Å. The typical grain size as revealed by scanning electron microscopy is in the range of 0.5–2 μm. The ρ–T behaviour shows a peak at TIM=227 K. The ρ–T behaviour above this temperature corresponds to that of an insulator and below this to that of a metal. The ρ–T behaviour remains unaltered when a magnetic field (Hdc=1.5 kG) is applied. However, with this magnetic field a drop in the resistivity is observed up to 77 K. At room temperature the magnetoresistance ratio (MRR) is too small but it steadily increases as the temperature is decreased. Thus, MRRs at 227.13 and 77 K are 3.41 and 9.05%, respectively, in an applied field of Hdc=1.5 kG. At a given temperature the variation in MRR with field Hdc is rapid at lower field values (Hdc<1.2 kG) and scales linearly for higher field values (Hdc>1.2 kG). It may be mentioned that the present work on the synthesis and magnetoresistance behaviour of La0.7Hg0.3MnO3, is the first of its type. |
| |
Keywords: | Transition metal compounds Synthesis Magnetically ordered materials Magnetoresistance X-Ray diffraction |
本文献已被 ScienceDirect 等数据库收录! |
|