Multiferroicity in atomic van der Waals heterostructures

Abstract

Materials that are simultaneously ferromagnetic and ferroelectric – multiferroics – promise the control of disparate ferroic orders, leading to technological advances in microwave magnetoelectric applications and next generation of spintronics. Single-phase multiferroics are challenged by the opposite d-orbital occupations imposed by the two ferroics, and heterogeneous nanocomposite multiferroics demand ingredients’ structural compatibility with the resultant multiferroicity exclusively at inter-materials boundaries. Here we propose the two-dimensional heterostructure multiferroics by stacking up atomic layers of ferromagnetic Cr ₂Ge ₂Te ₆ and ferroelectric In ₂Se ₃, thereby leading to all-atomic multiferroicity. Through first-principles density functional theory calculations, we find as In ₂Se ₃ reverses its polarization, the magnetism of Cr ₂Ge ₂Te ₆ is switched, and correspondingly In ₂Se ₃ becomes a switchable magnetic semiconductor due to proximity effect. This unprecedented multiferroic duality (i.e., switchable ferromagnet and switchable magnetic semiconductor) enables both layers for logic applications. Van der Waals heterostructure multiferroics open the door for exploring the low-dimensional magnetoelectric physics and spintronic applications based on artificial superlattices.

Abstract

Low dimensional multiferroic materials promise the technological advances in next generation spintronic and microwave magnetoelectric devices. Here the authors propose the multiferroicity in the atomically thin ferromagnetic Cr2Ge2Te6/ferroelectric In2Se3 van der Waals heterostructure due to the crosslayer magnetoelectric coupling.