Temperature Stability of Exchange Bias Field and Magnetoresistance of Fe20Ni80 Layer in Fe20Ni80/Tb–Co Films

The evolution of hysteresis and magnetoresistive properties of exchange-coupled Fe₂₀Ni₈₀/Tb-Co bilayers with modified interface was investigated in the temperature range from 79 to 450 K. Exchange bias field was shown to decrease monotonously with increasing temperature, demonstrating a very similar behavior for unmodified films and samples with ultrathin Ti spacer or selectively annealed permalloy layer. The observed dependence, therefore, is mostly attributed to the changes of the Tb-Co layer´s magnetization and magnetic anisotropy. Anisotropic magnetoresistance (AMR) value measured on all samples shown typical for the permalloy alloy reduction at higher temperatures regardless of the sample´s type. A simultaneous decrease of the exchange bias field and the value of the AMR effect was shown to open the possibility for the compensation of the temperature dependence of the medium´s response to the application of the external magnetic field.