We report on the observation of a field-induced magnetic bias effect in a Ga0.94Mn0.06As1-yPy thin film with digitally graded phosphorus content. Although phosphorus concentration in the sample is changed in steps from y≈0.03 to y≈0.28, the magnetometry and magnetotransport data display a coherent magnetic response typical for single-layer in-plane magnetized films with cubic and weak  uniaxial anisotropy. Unexpectedly, low-temperature planar Hall resistance loops exhibit remarkable asymmetry tunable by application of strong in-plane initial magnetic field HIni. We discuss this unusual memory effect, resembling the magnetization asymmetry in the exchange biased magnetic bilayers, in terms of a unidirectional bias field Hb induced by HIni. We show that such bias field defines the delayed or accelerated nucleation of domains with chiral domain walls performing the magnetization reversal.
Bibliographical noteFunding Information:
The work at University of Notre Dame was supported by the NSF Grant No. DMR14-00432. The work at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, Materials Sciences and Engineering Division. The work at Nanjing University was supported by National Natural Science Foundation of China (Grants No. 61771235 and No. 61727805) and the National Key R&D Program of China (2018YFA0209002). The work at Korea University was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2018R1D1A1A02042965) and by Ministry of Science ICT (2018R1A4A1024157). We appreciate constructive comments and suggestions from Ulrich Welp, Xiang Li, and Taehee Yoo. The data that support the findings of this study are available from the corresponding authors upon reasonable request.
© 2019 American Physical Society.
ASJC Scopus subject areas
- Materials Science(all)
- Physics and Astronomy (miscellaneous)