Correlation between MI Effect and Transverse Anisotropy in Stress-Annealed Nanocrystalline Alloys: A Mössbauer Effect Study

In order to understand the correlation between the large and sensitive magneto-impedance (MI) effect in the tensile stress-annealed Fe-based nanocrystalline alloy Fe73.5Cu1Nb3Si13.5B9 and the transverse magnetic anisotropy on a microscopic scale, a Mössbauer effect study has been carried out. A series of ribbon samples were subject to thermal annealing with tensile stress s up to 60 MPa. MI measurements showed that the effective field of transverse magnetic anisotropy Hk increases with increasing s. Analysis of Mössbauer spectra provided direct evidence that there is an increasing transverse magnetic structure with increasing s in these tensile stress-annealed samples. This work confirms, on the microscopic scale, that the transverse magnetic anisotropy arises from stress-annealing and is essential for the giant magneto-impedance effect.