Temperature dependence of the magnetic properties and magnetoimpedance of nanocrystalline Fe$_{73.5}$Si$_{16.5}$B$_6$Nb$_3$Cu$_1$ ribbons

The temperature dependences of the magnetic properties and the magnetoimpedance effect of soft magnetic nanocrystalline Fe$_{73.5}$Si$_{16.5}$B$_6$Nb$_3$Cu$_1$ alloy ribbons are studied in the temperature range 24–160$^\circ$C. A high temperature sensitivity of the impedance and the magnetoimpedance effect of the ribbons are detected in the ac frequency range 0.1–50 MHz. At an ac frequency of 50 MHz, the change in the impedance reaches 0.2 $\Omega$/$^\circ$C (0.5%/$^\circ$C) in the temperature range 85–160$^\circ$C. When the temperature increases, a monotonically decreasing character of the dependence of the magnetoimpedance effect on the applied magnetic field changes into a dependence having an increasing initial segment. The effect of temperature on the magnetoimpedance properties of the soft magnetic nanocrystalline ribbons is shown to result from temperature-induced changes in their electrical conductivity, magnetization, and effective magnetic anisotropy.