Temperature dependent orbital degree of freedom in a bilayer manganite by magnetic Compton scattering

TL;DR

This study uses temperature-dependent magnetic Compton scattering to reveal changes in specific $d$-electron states in a bilayer manganite, demonstrating a new way to probe orbital degrees of freedom in complex magnetic materials.

Contribution

It shows that magnetic Compton scattering can selectively monitor the occupancy of specific orbital states in a complex material over a range of temperatures.

Findings

Significant temperature-dependent changes in $d_{x^2-y^2}$ orbital occupancy.

Magnetic Compton profiles can distinguish specific orbital contributions.

The method provides insights into orbital degrees of freedom in manganites.

Abstract

We have measured temperature-dependent magnetic Compton profiles (MCPs) from a single crystal of La$_{1.2}$Sr$_{1.8}$Mn$_2$O$_7$. The MCPs, which involved the scattering of circularly polarized x-rays, are in general related to the momentum density of all the unpaired spins in the system. Nevertheless, we show that when the x-ray scattering vector lies along the [110] direction, the number of magnetic electrons of a specific symmetry, i.e. $d$-electrons of $x^2-y^2$ symmetry, yield a distinct signature in the MCP, allowing us to monitor substantial changes in the occupancy of the $d_{x^2-y^2}$ states over the investigated temperature range of 5-200K. This study indicates that magnetic Compton scattering can provide a powerful window on the properties of specific magnetic electrons in complex materials.