Intrinsic inhomogeneity and non-linear conduction in charge-ordered Bi 0.5Ca 0.4Sr 0.1MnO 3

Abstract

Systematic studies of X-ray, magnetic, electronic transport, and elastic properties have been performed on polycrystalline Bi 0.5Ca 0.4Sr 0.1MnO 3 sample. The sample exhibits charge ordering (CO) state below T CO (=304 K), accompanied by a distinct maximum in magnetization. The softening of Young's modulus in the vicinity of T CO indicates that there is a strong coupling of electron–phonon due to Jahn–Teller (JT) effect. The dynamic ferromagnetic spin correlations are observed at high temperatures above T CO, which are replaced by antiferromagnetic (AFM) spin fluctuations at a concomitant CO transition. Below 32 K, a spin-glass (SG) state dominates at low temperatures. The voltage–current ( V– I) characteristics measurement results indicate that the non-linear conduction starts above a threshold current, giving rise to a region of negative differential resistance (NDR). The origin of the non-linear conduction is discussed in view of current induced collapse of CO state associated with phase-separation mechanism.