Magnetic, magnetocaloric and critical behavior investigation of Nd0.7Ca0.15Sr0.15MnO3 prepared by high-energy ball milling

Abstract

Magnetic, magnetocaloric and critical behavior properties of Nd0.7Ca0.15Sr0.15MnO3polycrystalline prepared by high-energy ball milling are studied. The current study is a comparison between two different ball-milling times (4h milling and 24h, NCSMO1 and NCSMO2, respectively). Phase purity and structure are investigated using X-ray diffraction (XRD). The Rietveld refinements of the X-ray diffraction patterns show that our samples crystallize in the orthorhombic structure with ‘Pnma’ space group. Both compounds NCSMO1 and NCSMO2, exhibit a clear ferromagnetic (FM)-paramagnetic (PM) transition. The Curie temperature (TC) increased slightly with increasing milling time from 123K to 127K, for NCSMO1 and NCSMO2 respectively. Moreover, the magnetic entropy change (−ΔSM) and the relative cooling power (RCP) decreased slightly with increasing milling time. A detailed critical behavior study around TC has been conducted. The critical exponents β, γ and δ have been determined using various techniques such as the modified Arrott plot (MAP), the Kouvel-Fisher methods (KF) as well as the critical isotherm (CI). The values of critical exponents are close to the Tricritical mean-field and the 3d-Ising models for NCSMO1 and NCSMO2, respectively. On the basis of these critical exponents, the magnetization, field and temperature data (M-H-T) around TC collapse onto two curves (one for T<TC and another for T>TC) obeying the single scaling equation M(μ0H,ε)=(ε)βf±(μ0H/εβ+γ), thus confirming that the obtained values of β, γ and δ are reasonably accurate and unambiguous.