Pressure-induced insulating state in (La,Sr)CoO${}_3$

Abstract

We have investigated the effect of pressure on the electronic, magnetic, and structural properties on a single crystal of conducting, ferromagnet (T${}_C$=157K) La${}_{0.82}$Sr${}_{0.18}$CoO${}_3$ located near the boundary of the metal-insulator transition. Contrary to the results reported on related systems, we find a transition from the conducting state to an insulating state and a decrease of T${}_C$ with increasing pressure while the lattice structure remains unchanged. We show that this unusual behavior is driven by a gradual change of the spin state of Co${}^{3+}$ ions from magnetic intermediate-spin (t${}_{2g}^5$e${}_g^1$; S=1) to a nonmagnetic low-spin (t${}_{2g}^6$e${}_g^0$; S=0) state.

12 pages