Large negative anisotropic magnetoresistance in collinear antiferromagnet MnPt

Antiferromagnetic (AFM) spintronics offers a promising route to ultrafast, scalable information

storage and processing. However, quantitative data on key material parameters for many

collinear AFMs remains limited due to challenges in controlling the Néel vector. Here, we show

that measurements of the angular dependence of resistance and ferromagnetic resonance

(FMR) in MnPt|CoFeMnSi bilayers enable probing of anisotropic magnetoresistance (AMR) and

magnetocrystalline anisotropy (MCA) in the high-temperature MnPt AFM. Epitaxial L1 0 -MnPt

films were grown onto MgAl 2 O 4 (100) substrates, followed by deposition of amorphous

CoFeMnSi ferromagnet used as an exchange coupling layer to manipulate the AFM Néel

vector. Thickness- and angular-dependent transport measurements of the bilayers allow us to

quantify the intrinsic AMR value of MnPt, while FMR reveals a negative uniaxial perpendicular

and 4-fold in-plane MCA of the MnPt film. Density functional theory calculations are in good

agreement with the experimental MCA values. Our measurements reveal that MnPt exhibits a

record-high room-temperature negative AMR and a strong 4-fold MCA, making it an ideal

candidate for AFM spintronic devices.