Embedded magnetic phases in (Ga,Fe)N: Key role of growth temperature

Article

关键词: MOLECULAR-BEAM EPITAXY;    THERMAL-EXPANSION;    FERROMAGNETISM;    SEMICONDUCTORS;    IRON;    FE;    DIFFRACTION;    TRANSITION;    GAN;    ANTIFERROMAGNETISM;   

DOI  :  10.1103/PhysRevB.81.205206

来源: SCIE

【 摘 要 】

The local chemistry, structure, and magnetism of (Ga,Fe)N nanocomposites grown by metal-organic vapor-phase epitaxy are studied by synchrotron x-ray diffraction and absorption, high-resolution transmission electron microscopy, and superconducting quantum interference device magnetometry as a function of the growth temperature T-g. Three contributions to the magnetization are identified: (i) paramagnetic-originating from dilute and noninteracting Fe3+ ions substitutional of Ga and dominating in layers obtained at the lowest considered T-g (800 degrees C); (ii) superparamagneticlike-brought about mainly by ferromagnetic nanocrystals of epsilon-Fe3N but also by gamma'-Fe4N and by inclusions of elemental alpha-Fe, and prevalent in films obtained in the intermediate T-g range; (iii) component linear in the magnetic field and associated with antiferromagnetic interactions-found to originate from highly nitridated FexN (x <= 2) phases, like zeta-Fe2N, and detected in samples deposited at the highest employed temperature, T-g=950 degrees C. Furthermore, depending on T-g, the Fe-rich nanocrystals segregate toward the sample surface or occupy two-dimensional planes perpendicular to the growth direction.

【 授权许可】

Free