Significant high-frequency electromagnetic wave absorption performance of Ni 2+ x Mn 1− x Ga alloys

The electromagnetic wave (EMW) absorption properties in Heusler-type ferromagnetic Ni2+xMn1−xGa alloys were systematically investigated. Significant electromagnetic absorption performance at 2.0–18.0 GHz was observed for Ni2+xMn1−xGa alloys. The values of the complex permittivity (e r ) and permeability (μ r ), as well as the reflection loss (RL), peak frequency (fm) and bandwidth (Δf) of Ni2+xMn1−xGa can be effectively tuned by the alloy component (Ni/Mn ratio). The magnetic loss factor (tan δ μ ) shows pronounced multi-resonance behavior, and dielectric loss factor (tan δ e ) has dramatic dielectric relaxation. The RL exceeding − 10 dB corresponding to 90% absorption of incident microwave can be achieved for the Ni2MnGa in a broad frequency range of 6.3–18.0 GHz together with the thickness from 1.66 to 4.75 mm. Particularly, the maximum RL reaches − 49.1 dB at 13.3 GHz with the thickness of 2.57 mm for Ni2MnGa. The present results indicated that the ferromagnetic Ni2+xMn1−xGa alloys could be attractive candidates for broadband and high-frequency EMW absorption.