A novel CrSeFe bilayer structure has been fabricated on a GaAs (100) substrate by the molecular beam epitaxy technique. Microstructural characterizations have revealed that the Fe layer is a single-crystalline bcc structure with the orientation relationship of (100)Fe ∥ (100)GaAs, while the top CrSe layer shows four preferred hexagonal domains with their c axis each along one of the four upward-pointing 〈111〉 directions of the underlying Fe lattice. The magnetic hysteresis loops of this bilayer structure measured by a superconducting quantum interference device magnetometer demonstrate a strong exchange bias effect with a negative exchange bias field as high as -48.4 Oe at 5 K. The magnetization reversal process shows an abrupt transition nature at temperature from 5 to 300 K. An enhancement of the coercivity not accompanied by the exchange bias field was observed at temperature higher than and well above the blocking temperature. We have interpreted these observations based on the well-established exchange spring model for antiferromagnetic/ferromagnetic bilayer structures.
Bibliographical noteFunding Information:
The MBE growth was performed in the Zheng Ge Ru Thin Film Physics Laboratory at HKUST. The authors are grateful to the technical assistance from the staff in the Materials Characterization and Preparation Facilities at HKUST. The work described here was substantially supported by grants from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project Nos. HKUST6064/02P and 605605).
ASJC Scopus subject areas
- Physics and Astronomy(all)