Spin-glass and ferromagnetic behavior of Ni-Mn multilayered films

• Published in: Journal of applied physics 1985-01, Vol.57 (8), p.3441-3443
• Main Authors: Vernon, S. P., Halawith, B. N., Stearns, M. B.
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.335070

We report a detailed investigation of the temperature T and field H dependence of the magnetization of equal layer thickness Ni-Mn multilayered films with modulation wavelengths of 50(25–25) and 26(13–13) A, and overall film thickness of approximately 1 μm. The dc magnetization was measured for T between 1.6 and 400 K, for H between ±30 kOe using a SHE VTS-968 SQUID magnetometer. Both samples exhibit spin-glass behavior at low temperatures: Cooling the films in an applied magnetic field displaces the hysteresis loop and the saturation magnetization is reduced at low T. Both films undergo a transition to ferromagnetic (FM) behavior as the temperature is increased above ∼20 K. At higher T, the 13–13 A sample behaves like a ‘‘normal’’ FM, but the 25–25 A film behaves like a ‘‘biased’’ FM; that is, the hysteresis loop continues to be displaced, along the H axis. The displacement gradually decreases with increasing T. The experimental observations are consistent with there being systematic concentration variations in each compositionally modulated film which give rise to adjacent FM and antiferromagnetic regions as well as an interfacial spin-glass-like region.