Sudip Pandey; Abdiel Quetz; Anil Aryal; Ahmad Us Saleheen; Igor Dubenko; Dipanjan Mazumdar; Shane Stadler; Naushad Ali
Abstract
The effects of substituting Cu for Mn on the magnetocaloric, transport, and thermomagnetic properties of Ni50Mn35-xCuxIn14B (x = 0, 1.25, 2.0) Heusler alloys were studied. It has been found that the magnitude of the magnetization jump at the martensitic transformation decreased with increasing Cu concentration. ...
Read More
The effects of substituting Cu for Mn on the magnetocaloric, transport, and thermomagnetic properties of Ni50Mn35-xCuxIn14B (x = 0, 1.25, 2.0) Heusler alloys were studied. It has been found that the magnitude of the magnetization jump at the martensitic transformation decreased with increasing Cu concentration. Smaller magnetic entropy changes (∆SM) were observed for the alloys with higher Cu concentrations. A decrease in the resistivity was observed with increasing Cu concentration. The magnetoresistance was dramatically suppressed with increasing Cu concentration due to the weakening of the antiferromagnetic (AFM) interactions in the martensitic phase. The experimental results demonstrate that Cu in Ni50Mn35-xCuxIn14B Heusler alloys suppresses the AFM interactions and enhances the ferromagnetic (FM) interactions in these alloys. Possible mechanisms responsible for the observed behavior are discussed.
S. Yadam; Durgesh Singh; D. Venkateshwarlu; M. Gangrade; S. S. Samatham; V. Ganesan
Abstract
CeNi2Al3 system is a potential candidate for low temperature thermoelectrics. Substitution studies, especially at the Ni site are considered to be of importance due to the drastic tuning of its physical properties. Resistivity in magnetic fields and thermoelectric power measurements of Cu doped CeNi2Al3 ...
Read More
CeNi2Al3 system is a potential candidate for low temperature thermoelectrics. Substitution studies, especially at the Ni site are considered to be of importance due to the drastic tuning of its physical properties. Resistivity in magnetic fields and thermoelectric power measurements of Cu doped CeNi2Al3 (x=0.0 to 0.4) system is reported in this investigation. This dense Kondo lattice system is investigated with an aim of understanding its basic transport mechanism. Negative magnetoresistance is seen for x=0.3 and 0.4 in the magnetic field up to 14 T. Deviation from the Kondo behavior occurs at temperatures close to 2 K with a down turn in resistivity. The nature of resistivity at low temperatures is investigated in view of the possible evidence for Fermi liquid behavior and also the formation of heavy Fermion in corroboration with specific heat studies. Doping dependence of linear diffusion coefficient and Sommerfeld coefficient of specific heat are analyzed and discussed in connection with the heavy Fermion formation. The results obtained show a promising trend in tuning these materials by way of Kondo route as well as by the substitution especially at the Ni site in the present system.
Maneesha Gupta; Poonam Yadav; Wasi Khan; Ameer Azam; Alim H. Naqvi; R. K. Kotnala
Abstract
We have synthesized La1-xSrxMnO3 (with x=0.3, 0.33 & 0.4) perovskite nanoparticles using mild sol-gel technique at low temperature and thereby studied the effect of nanosize on magnetoresistance. These samples were characterized using TGA/DSC, XRD, TEM, FTIR and temperature dependent magnetoresistance ...
Read More
We have synthesized La1-xSrxMnO3 (with x=0.3, 0.33 & 0.4) perovskite nanoparticles using mild sol-gel technique at low temperature and thereby studied the effect of nanosize on magnetoresistance. These samples were characterized using TGA/DSC, XRD, TEM, FTIR and temperature dependent magnetoresistance (MR) measurements. Powder X-ray diffraction (XRD) result confirms the formation of pure crystalline phase with rhombohedral symmetry in R-3C space group. Crystallite size increases with increase in Sr concentration. TEM analysis further supports the nanosized particles in the samples which lie in the range of 20-30 nm. Fourier transform infrared (FTIR) spectroscopy shows a broad peak at 615 cm -1 for all the samples gives an evidence for the formation of metal oxygen bond organized in to MnO6 octahedral. The steep change in magnetoresistance (MR) at low field at low temperature is observed which is attributed to the alignment of the spins, while in the high field MR is due to the grain boundaries effect at low temperature. In the series studied, 33% Sr doped sample shows higher MR both at low temperature (-17.15) and room temperature (-3.07) than their counter parts.