Magnetoelastic polarons in the hole-doped quasi-one dimensional model system Y2-xCaxBaNiO5

TL;DR

This study investigates charge transport in hole-doped Y$_{2-x}$Ca$_x$BaNiO$_5$, revealing magnetoelastic polarons' role and proposing a semi-classical model linking electrical and magnetic properties in a quasi-1D system.

Contribution

It introduces a semi-classical model that connects electrical measurements with magnetic susceptibility, elucidating the spin-charge-lattice interactions in doped quasi-1D materials.

Findings

Activation energy decreases with cooling.

Doped holes form magneto-acoustic polarons.

The model explains the charge excitation spectrum.

Abstract

Charge transport in the hole-doped quasi-1D model system Y$_{2-x}$Ca$_x$BaNiO$_5$ (x $ leq$ 0.15) is investigated in the 50-300 K temperature range. The resistivity temperature dependence is characterized by a constant activation energy $E_{a}/k_{B} sim$ 1830 K at room temperature while $E_{a}$ decreases upon cooling. We suggest that $E_{a}$ measures the binding energy of the doped holes which form magneto-acoustic polarons when polarizing the neighboring Ni spins. A semi-classical model is proposed which allows to relate the electrical measurements and the bulk magnetic susceptibility. This model gives a picture of the spin-charge-lattice relation in this inhomogeneously doped quasi-1D system and explains its unusual one-particle charge excitation spectrum close to the Fermi level.