# Thermopower of the electron-doped manganese pnictide LaMnAsO

## TL;DR

This study combines experimental doping of LaMnAsO with advanced theoretical methods to explain its high thermopower, revealing the role of electronic correlations and spectral asymmetry in this process.

## Contribution

It provides a detailed theoretical explanation for the high Seebeck coefficient in electron-doped LaMnAsO, highlighting the importance of electronic correlations.

## Key findings

- High Seebeck coefficient of around -300 μV/K at 3% doping
- Spectral asymmetry caused by incoherent spectral weight and renormalization of unoccupied states
- Correlated electron effects are essential to explain thermopower in this material

## Abstract

Upon chemical substitution of oxygen with fluor, LaMnAsO has been electron-doped in experiments, resulting in samples with remarkably high Seebeck coefficients of around -300$\mu VK^{-1}$ at room temperature and 3% doping. Within the framework of density functional theory plus dynamical mean-field theory we are not only able to reproduce these experimental observations, but can also provide a thorough investigation of the underlying mechanisms. By considering electronic correlations in the half-filled Mn-3d shells, we trace the high Seebeck coefficient back to an asymmetry in the spectral function, which is due to emergence of incoherent spectral weight under doping and a strong renormalisation of the unoccupied states. This is only possible in correlated systems and cannot be explained by DFT-based band structure calculations.