Raman fingerprints of spin-phonon coupling and magnetic transition in an organic molecule intercalated Cr2Ge2Te6

TL;DR

This study demonstrates how organic intercalation in Cr2Ge2Te6 enhances spin-phonon coupling and magnetic transition properties, revealed through Raman spectroscopy and supported by first-principles calculations, advancing understanding of layered magnetic heterostructures.

Contribution

It provides spectroscopic and theoretical evidence of intercalation-induced enhancement of spin-phonon coupling and magnetic transition in a 2D van der Waals ferromagnetic material.

Findings

Enhanced ferromagnetic Curie temperature in intercalated Cr2Ge2Te6

Increased spin-phonon interaction evidenced by Raman modes

Electron transfer from TBA+ to Cr at the interface

Abstract

The manipulation of spin-phonon coupling in both formations and explorations of magnetism in two-dimensional van der Waals ferromagnetic semiconductors facilitates unprecedented prospects for spintronics devices. The interlayer engineering tunes spin-phonon coupling significantly and holds the promise for controllable magnetism via organic cation intercalation. Here, we present spectroscopic evidence to reveal the intercalation effect on intrinsic magnetic and electronic transitions in quasi-two-dimensional Cr2Ge2Te6 using tetrabutyl ammonium as the intercalant. The temperature-evolution of Raman modes E_g^3 and A_g^1, along with the magnetization measurements, unambiguously captures the enhancement of the ferromagnetic Curie temperature in the intercalated heterostructure. Moreover, the E_g^4 mode highlighted the increased effect of spin-phonon interaction in magnetic order-induced lattice distortion. Combined with the first-principle calculations, we observed a substantial number of electrons transferred from TBA+ to Cr through the interface. These results provide the interplay between spin-phonon coupling and magnetic ordering in van der Waals magnets where Raman fingerprints would be highly beneficial for further understanding the manipulation of magnetism in layered heterostructures.