Nonequilibrium 1/f Noise in Low-doped Manganite Single Crystals

TL;DR

This study investigates 1/f noise in low-doped manganite crystals, revealing that resistivity fluctuations dominate the noise behavior and that nonequilibrium effects emerge at low temperatures and high biases due to tunneling mechanisms.

Contribution

It provides new insights into the temperature and bias dependence of 1/f noise in manganite crystals, highlighting the role of tunneling in nonequilibrium noise phenomena.

Findings

Resistivity fluctuations account for the 1/f noise across temperatures.

Noise scales with the square of the current, indicating equilibrium fluctuations.

At 77 K, high bias induces a decrease in noise due to tunneling effects.

Abstract

1/f noise in current biased La0.82Ca0.18MnO3 crystals has been investigated. The temperature dependence of the noise follows the resistivity changes with temperature suggesting that resistivity fluctuations constitute a fixed fraction of the total resistivity, independently of the dissipation mechanism and magnetic state of the system. The noise scales as a square of the current as expected for equilibrium resistivity fluctuations. However, at 77 K at bias exceeding some threshold, the noise intensity starts to decrease with increasing bias. The appearance of nonequilibrium noise is interpreted in terms of bias dependent multi-step indirect tunneling.