Valence instability of cerium under pressure in the Kondo-like perovskite La${}_{0.1}$Ce${}_{0.4}$Sr${}_{0.5}$MnO${}_3$

Abstract

Effect of hydrostatic pressure and magnetic field on electrical resistance of the Kondo-like perovskite manganese oxide, La${}_{0.1}$Ce${}_{0.4}$Sr${}_{0.5}$MnO${}_3$ with a ferrimagnetic ground state, have been investigated up to 2.1 GPa and 9 T. In this compound, the Mn-moments undergo double exchange mediated ferromagnetic ordering at $T_{\mathrm{C}}$ $\sim$ 280 K and there is a resistance maximum, $T_{\max }$ at about 130 K which is correlated with an antiferromagnetic ordering of {\it cerium} with respect to the Mn-sublattice moments. Under pressure, the $T_{\max }$ shifts to lower temperature at a rate of d$T_{max}$/d$P$ = -162 K/GPa and disappears at a critical pressure $P_{\mathrm{c}}$ $\sim$ 0.9 GPa. Further, the coefficient, $m$ of $-logT$ term due to Kondo scattering decreases linearly with increase of pressure showing an inflection point in the vicinity of $P_{\mathrm{c}}$. These results suggest that {\it cerium} undergoes a transition from Ce${}^{3+}$ state to Ce${}^{4+}$/Ce${}^{3+}$ mixed valence state under pressure. In contrast to pressure effect, the applied magnetic field shifts $T_{\max }$ to higher temperature presumably due to enhanced ferromagnetic Mn moments.

to be published in Phys. Rev. B (rapid commun)