Atomic-Scale Detection of Néel Vector Switching in the Single-Layer A-Type Antiferromagnet Cr₂S₃-2D.

Abstract

The detection of Néel vector switching in a single-layer A-type antiferromagnet marks an important step toward functional two-dimensional spintronics. Here, <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow><msub><mi>Cr</mi> <mn>2</mn></msub> <msub><mi>S</mi> <mn>3</mn></msub> </mrow> </math> -2D, grown on graphene on Ir(110), is established as a first single-layer A-type antiferromagnet. Spin-polarized scanning tunneling microscopy reveals hysteresis loops with a large switching field and a pronounced dependence on island size. X-ray magnetic circular dichroism at the Cr <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>L</mi> <mrow><mn>2</mn> <mo>,</mo> <mn>3</mn></mrow> </msub> </math> edges exhibits a tiny signal with a linear magnetic field dependence, consistent with an antiferromagnetic ground state with an estimated net moment below <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow><msup><mn>10</mn> <mrow><mo>-</mo> <mn>2</mn></mrow> </msup> <msub><mi>μ</mi> <mi>B</mi></msub> </mrow> </math> per Cr and a Néel temperature of about 160 K. Quantitative analysis of the island-size dependence of the switching field, together with first-principles calculations, indicates a slight imbalance between the magnetic moments of the two Cr planes of <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow><msub><mi>Cr</mi> <mn>2</mn></msub> <msub><mi>S</mi> <mn>3</mn></msub> </mrow> </math> -2D when supported on a substrate. This imbalance results in a net magnetization for the A-type antiferromagnet, which enables the 180 <math xmlns="http://www.w3.org/1998/Math/MathML"><msup><mrow></mrow> <mo>∘</mo></msup> </math> rotation of the Néel vector. Moreover, <math xmlns="http://www.w3.org/1998/Math/MathML"> <mrow><msub><mi>Cr</mi> <mn>2</mn></msub> <msub><mi>S</mi> <mn>3</mn></msub> </mrow> </math> -2D retains its magnetic properties after several days of exposure to air.