Quantum spin excitations in a dual-core magnetic molecule

TL;DR

This study investigates quantum spin excitations in a dual-core Cr2Br6 molecule using advanced microscopy and theoretical methods, revealing complex magnetic behaviors and potential for quantum applications.

Contribution

It provides the first detailed experimental and theoretical analysis of quantum spin excitations in a dual-core magnetic molecule, highlighting its potential for quantum technologies.

Findings

Observation of Fano peaks with multi-steps in STS

Magnetic field induces splitting in some steps

Identification of vibrational and magnetic excitation coexistence

Abstract

Magnetic excitations are important quantum phenomena in magnetic systems and have been widely studied in individual magnetic atoms and molecules as well as their assembled structures over the past few decades. Using scanning tunneling microscopy/spectroscopy (STM/S) combined with density functional theory (DFT) and the state-of-the-art ab initio wavefunction calculations, we investigated the properties of a novel dual-core Cr2Br6 molecule, which consists of two Cr ions coupled via superexchange through a single near-90{\deg} Cr-Br-Cr scissors bond. Under zero magnetic field, we observed a Fano peak with multi-steps through STS. When an external magnetic field is applied, some steps exhibit additional splitting, while others change little. We find that the Cr2Br6, exhibits a spin-degenerate ground state, and the complex peak splitting arises from the coexistence of vibrational and magnetic excitations in the molecule. Our results reveal rich quantum spin behavior in a well-defined two-core magnetic trihalide complex at the atomic scale, offering not only a minimal model for superexchange-coupled multi-spin quantum excitations but also a possible foundational unit for future molecule-based quantum functionalities.