Investigation of the magnetic anisotropy in ferromagnetic GaMnAs films by using the planar hall effect

• Published in: Journal of the Korean Physical Society Vol. 62; no. 12; pp. 2099 - 2103
• Main Authors: Won, Jaehyuk, Shin, Jinsik, Gwon, Yoonjung, Byeon, Hyehyeon, Lee, Sangyeop, Lee, Sanghoon, Liu, X., Furdyna, J. K.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.06.2013; 한국물리학회
• Subjects: Mathematical and Computational Physics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Theoretical; 물리학; Planar Hall effect; Ferromagnetic semiconductor; Magnetic anisotropy
• ISSN: 0374-4884; 1976-8524
• DOI: 10.3938/jkps.62.2099

The magnetic anisotropy properties of GaMnAs ferromagnetic films have been investigated by using planar Hall effect measurements. The field scan of the planar Hall resistance (PHR) showed a two-step switching behavior indicating a strong cubic anisotropy along the 〈100〉 directions. The difference in the behaviors of the PHR for two applied field directions, and [110], was understood via the well-known uniaxial anisotropy along the [110] direction. In addition to such known effects, we also found the presence of an asymmetry for the [010] and the [100] directions. This new asymmetry phenomenon was explained by introducing an additional uniaxial anisotropy field H u 2 along the [100] and the directions, which coincide with the two directions of cubic anisotropy. The values of the anisotropy fields, cubic ( H c ), first uniaxial ( H u 1 ), and second uniaxial ( H u 2 ), were obtained by analyzing the angle dependence of the PHR. Although the value of H u 2 is small, its effect is clearly observed at high temperatures above 25 K, where the transition of the magnetization occurred before the field direction had been reversed during the magnetization reversal process.