3D-Heisenberg ferromagnetic characteristics in a La$_{0.67}$Ba$_{0.33}$MnO$_{3}$ film on SrTiO$_{3}$

Abstract

We conducted a study of critical exponents to investigate the nature of paramagnetic to ferromagnetic phase transition in a La$_{\mathrm{0.67}}$Ba$_{\mathrm{0.33}}$MnO$_{\mathrm{3}}$ (LBMO) film deposited on SrTiO$_{\mathrm{3}}$. To this end, we performed dc magnetization M (H, T) measurements around the Curie temperature ($T_{\mathrm{C}}\sim$ 276.5 K) within a temperature range that includes the critical region $|\varepsilon |$ $=$ $|T-T_{\mathrm{C}}|$/$T_{\mathrm{C}} < 0.05$. We found that the transition is a second-order transition. Three main critical exponents, namely $\beta$ (0.387), $\gamma$ (1.309) and $\delta$ (4.634), and the critical temperature $T_{\mathrm{C}} =$ 276.6 K are derived from the modified Arrott plots. These exponents obey the Widom relation $\delta =$ 1$+\gamma$/$\beta$ and are able to collapse a bunch of isothermal magnetization data into two branches below and above $T_{\mathrm{C}}$ based on the single scaling equation M(${H, \varepsilon }$)$\varepsilon ^{-\beta } = {f}_{\pm }({H} \varepsilon ^{({-\beta +\gamma })})$. The critical behavior in LBMO film is close to a 3D Heisenberg model, although certain long-range interactions still exist. Compared to a polycrystalline bulk sample, the long-range interactions are greatly suppressed, which may be attributed to the reduced dimensionality.

Graphic abstract