Magnetic Order and Dynamics in an Orbitally Degenerate Ferromagnetic Insulator

TL;DR

This study uses neutron scattering to analyze the complex magnetic structure and magnon spectrum of YTiO3, revealing inconsistencies with existing orbitally ordered models and impacting theories of exchange interactions in orbitally degenerate systems.

Contribution

It provides detailed experimental insights into the magnetic structure and magnon spectrum of YTiO3, challenging current orbitally ordered models and informing theoretical descriptions.

Findings

Magnetic structure includes G-type and A-type antiferromagnetic components

Magnon spectrum is gapless and nearly isotropic

Results are inconsistent with proposed orbitally ordered states

Abstract

Neutron scattering was used to determine the spin structure and the magnon spectrum of the Mott--Hubbard insulator YTiO$_3$. The magnetic structure is complex, comprising substantial G-type and A-type antiferromagnetic components in addition to the predominant ferromagnetic component. The magnon spectrum, on the other hand, is gapless and nearly isotropic. We show that these findings are inconsistent with the orbitally ordered states thus far proposed for YTiO$_3$ and discuss general implications for a theoretical description of exchange interactions in orbitally degenerate systems.