Influence of chemical pressure on the magnetism of Pr0.7Ca0.3−xSrxMnO3 (x = 0.0-0.3)

We have studied the effect of chemical pressure on the magnetic properties of a series of Pr0.7Ca0.3−xSrxMnO3 (x = 0.0-0.3) (PCSMO) compounds. The parent compound Pr0.7Ca0.3MnO3 (PCMO) is a well known charge-ordered compound. The selective substitution of Sr for Ca in PCMO leads to increase in electron count as a 4s metal (Ca) is being replaced by a 5s (Sr) alkali metal, resulting in melting of CO-state (in PCSMO) and increase in magnetic transition temperature (To) from 85 K (for x = 0.0) to 260 K (for x = 0.3). The lattice distortion factors, such as A-site variance (σ2) and tolerance factor (Tf) vary linearly with To. The magnetocaloric effect (MCE shown as, ΔS) calculated from isothermal magnetization measurement exhibits maximum (at T = To) for x = 0.2 for a field change from 0 to 50 kOe. The variation of ΔS(x) mimic the variation of ΔS(σ2), indicating the strong influence of Mn-O-Mn bond angle on the MCE. We discuss these results in terms of modification of magnetic properties in PCSMO through chemical pressure.