Tailing the Magnetoelectric Properties of Cr2Ge2Te6 by Engineering Covalently Bonded Cr Self-Intercalation: Ferromagnetic Half-Metal

Two-dimensional intrinsic ferromagnetic half-metals (HMs)are importantfor spintronics. Based on a systematic research of CrGeTe3 (CGT) bilayers and multilayers with the self-intercalated (SI) Cr(Cr-SI) atom, we find that self-intercalation can enhanceinterlayer magnetic coupling, which results in a super-exchange interactionbetween interlayers. The CGT bilayer keeps half-metallicity with theinterlayer ferromagnetic (FM) order after Cr's self-intercalation,independent of Cr-SI atoms' concentration and stackingorders. Moreover, SI-CGT multilayers with interlayer FM order transformfrom HMs into normal spin-polarized metals, as the states at the Fermilevel increase. Moreover, the magnetic anisotropy energies (MAEs)of SI-CGT-AA and SI-CGT-AB are -0.160 and -0.42 meV/f.u.,respectively, which are modulated by the Cr-SI atoms. TheMAEs of SI-CGT-AA and SI-CGT-AB are different, as the hybridizationinteractions between Cr's d orbitals are different from eachother. SI-CGT bilayers' magnetic easy axis (EA) switches fromthe original [001] of CGT to the [100] direction, independent of thestacking orders. It is inferred that the MAE is mainly contributedby the hybridization between Te's p( x ) and p( y ), p( y ) and p( z ) orbitals, and that this hybridizationinteraction is obviously weakened as Cr-SI atom is inserted.The SI-CGT bilayers and multilayers show good dynamic and thermalstability at 300 and 500 K. These findings offer a promising way tomanipulate the interlayer exchange interaction and magnetoelectricproperties of CGT multilayers and other vdW magnets.