Kitaev Magnetism and Fractionalized Excitations in Double Perovskite Sm2ZnIrO6

TL;DR

This paper provides experimental evidence of Kitaev spin liquid behavior in Sm2ZnIrO6, revealing a magnetic continuum and signatures of Majorana fermions through Raman spectroscopy, advancing understanding of fractionalized excitations in 3D materials.

Contribution

First experimental detection of Kitaev spin liquid features and Majorana fermions in a double perovskite structure using Raman measurements.

Findings

Observation of a broad magnetic continuum at low temperatures.

Anomalous phonon self-energy renormalization indicating spin fractionalization.

Evidence supporting the existence of Majorana fermions in the material.

Abstract

The quest for Kitaev spin liquids in particular three dimensional solids is long sought goal in condensed matter physics, as these states may give rise to exotic new types of quasi-particle excitations carrying fractional quantum numbers namely Majorana Fermionic excitations. Here we report the experimental signature of this characteristic feature of the Kitaev spin liquid via Raman measurements. Sm2ZnIrO6 is a strongly spin orbit coupled Mott insulator, where Jeff = 1/2 controls the physics, which provide striking evidence for this characteristic feature of the Kitaev spin liquid. As the temperature is lowered, we find that the spin excitations form a continuum in contrast to the conventional sharp modes expected in ordered antiferromagnets. Our observation of a broad magnetic continuum and anomalous renormalization of the phonon self-energy parameters evidence the existence of Majorana fermions from spin fractionalization in double perovskites structure as theoretically conjectured in a Kitaev-Heisenberg geometrically frustrated double perovskite systems.