arXiv subjects

Tapas Samanta

Publications and source records attributed to Tapas Samanta.

21 records · Page 2Linked to original sources

arXiv2009

Magnetocaloric properties of nanocrystalline La$_{0.125}$Ca$_{0.875}$MnO$_{3}$

Some recent experimental studies show the invisibility of antiferromagnetic transition in the cases of manganites when their particle size is reduced to nanometer scale. In complete contrast to these cases, we have observed the signature of antiferromagnetic transition in the magnetocaloric properties of nanocrystalline La$_{0.125}$Ca$_{0.875}$MnO$_{3}$ of average particle size 70 and 60 nm similar to its polycrystalline bulk form. The system exhibit inverse magnetocaloric effect in its polycrystalline and nanocrystalline form. An extra ferromagnetic phase is stabilized at low temperature for the sample with particle size $\sim 60$ nm.

cond-mat.mtrl-sci↗

arXiv2008

Asymptotic optimality of a cross-validatory predictive approach to linear model selection

In this article we study the asymptotic predictive optimality of a model selection criterion based on the cross-validatory predictive density, already available in the literature. For a dependent variable and associated explanatory variables, we consider a class of linear models as approximations to the true regression function. One selects a model among these using the criterion under study and predicts a future replicate of the dependent variable by an optimal predictor under the chosen model. We show that for squared error prediction loss, this scheme of prediction performs asymptotically as well as an oracle, where the oracle here refers to a model selection rule which minimizes this loss if the true regression were known.

math.ST↗

arXiv2006

Influence of Domain Wall on Magnetocaloric Effect in GdPt$_{2}$

The resistivity, magnetoresistance and in-field heat capacity measurements were performed on GdPt$_{2}$ intermetallic compound. The magnetocaloric parameters $ΔT_{ad}$ and $-ΔS$ were derived from the in-field heat capacity data. Comparison has been made between the magnetocaloric effect $-ΔS$ and difference in resistivity $-Δρ$ $(=ρ(H)-ρ(0))$ as a function of temperature. There is distinct difference in the temperature dependence of $-ΔS$ and $-Δρ$ below the ferromagnetic transition temperature. However after removing the domain wall contribution from $-Δρ$, the nature of $-ΔS$ and $-Δρ$ dependence as a function of temperature are similar. Our observation indicates that the domain wall contribution in magnetocaloric effect is negligible in spite of the fact that it has significant contribution in magnetotransport.

cond-mat.mtrl-sci↗