Magnetism


2D intrinsic magnetism has received a tremendous interest with recent discoveries of layer-dependent magnetic ordering and its electric field control. However, it is not very surprising that such systems present a magnetic response down to the atomically-thin limit, since their bulk parent materials were known to be magnetic as well. Defect engineering has been considered a promising approach to extrinsically introduce magnetism in otherwise non-magnetic materials. Recently, our work involving electrical measurements supported by first-principles calculations and aberration-corrected transmission electron microscopy imaging of point defects show the existence of either ferromagnetic or anti-ferromagnetic ground state orderings depending on the number of layers in defective 2D PtSe2. In contrast to available intrinsic magnets, this extrinsically induced material is air-stable and therefore promising for applications.

Combination of the defect-induced magnetism with unique thickness-dependent properties could have several applications for realizing spintronic devices using atomically thin materials. Thin semiconducting PtSe2 could be utilized as a magnetic substrate for proximity studies. On the other hand, thick metallic PtSe2 could be integrated into lateral and vertical spin torque devices, tunnelling magnetoresistance devices and spin valve devices to generate spin polarized charge carriers. We are interested in realizing van der Waals spintronics devices with sharp interfaces by utilizing both intrinsically and extrinsically magnetic layered materials.

Related Publications:

1. Highly anisotropic van der Waals magnetism, A. Avsar, Nature Materials, 21 (7), 731-733 (2022).

2. Probing magnetism in atomically thin semiconducting PtSe2, A Avsar, CY Cheon, M Pizzochero, M Tripathi, A Ciarrocchi, OV Yazyev, and A. Kis, Nature Communications, 11, 4806 (2020).

3. Defect induced, layer-modulated magnetism in ultra-thin metallic PtSe2, A. Avsar*, A. Ciarrocchi, M. Pizzochero, D. Unuchek, O. V. Yazyev, and A. Kis*, Nature Nanotechnology 14, 674-678 (2019).


A device schematics illustrating defect-induced, layer dependent magnetization in PtSe2. Bulk is non-magnetic. The competition between ferro- and antiferro-magnetic ground states stems from the RKKY exchange couplings between magnetic Pt vacancies located at the surface of metallic films of PtSe2. (Image prepared with A.C.).