Critical behavior of La1-xSrxMnO3 (0 ≤ x ≤ 0.35) by thermal diffusivity measurements -: art. no. 184402

An ac photopyroelectric calorimeter has been used to measure the thermal diffusivity of the perovskite manganite family La1-xSrxMnO3 on a set of single crystals with doping range 0less than or equal toxless than or equal to0.35. Taking into account that the inverse of the thermal diffusivity has the same critical behavior as the specific heat, the critical exponent alpha of the magnetic transitions has been obtained. The results point to short-range interaction models for pure magnetic transitions. In the pure and lightly doped samples (x<0.10), where the transition is antiferromagnetic-paramagnetic, the critical exponent is consistent with the Heisenberg model (alpha=-0.11). For the highly doped samples (x>0.28), where there is a pure ferromagnetic-paramagnetic transition, the critical exponent is exactly that of an Ising behavior (alpha=+0.11). For 0.10less than or equal tox<0.28 no universality class was found and this behavior has been discussed taking into account the complexity of the phase diagram in this concentration range.