Giant spontaneous exchange bias in an antiperovskite structure driven by a canted triangular magnetic structure

TL;DR

This study demonstrates a giant exchange bias effect in an antiperovskite material driven by a canted triangular magnetic structure, achieving significant magnetic shifts near room temperature without external field cooling.

Contribution

It reports the first observation of giant exchange bias in an antiperovskite material with a canted magnetic structure, highlighting a new strategy for room-temperature magnetic applications.

Findings

Giant exchange bias of 0.28 T at 50 K after zero-field cooling.

Exchange bias increased to 1.2 T with a small applied cooling field.

Correlation between exchange bias and vertical magnetization shift.

Abstract

Exchange bias (EB) refers to a shift of the hysteresis loop along the field axis in materials consisting of ferromagnetic (FM) and antiferromagnetic (AFM) layers, generally after a cooling procedure in high magnetic field. This effect is highly desirable for technological applications ranging from spintronics to magnetic recording. Achieving giant EB effect near room temperature in a small cooling field is thus an on-going technologically relevant challenge for the materials science community. In this work, we present the experimental realization of such a fundamental goal by demonstrating the existence of giant EB after a zero field cooled (ZFC) procedure in antiperovskite Mn3.5Co0.5N below 256 K. We found that it exhibits an EB field of 0.28 T at 50 K after a ZFC procedure accompanied by a large vertical magnetization shift (VMS). Interestingly, this EB field can be elevated up to 1.2 T after a cooling procedure with a small applied field of just 500 Oe. Mn3:5Co0:5N bears the first intermetallic material showing a strong correlation between EB and VMS.We attribute the observed EB effect to a completely new canted triangular magnetic structure determined by neutron diffraction experiment. Finally, we discuss the striking effect of Co substitution on the physical properties of antiperovskite materials and put forward a new strategy for antiperovskite lattice to exploit new single phase materials showing large EB effect at room temperature.