Effects of non-magnetic phase and deposition temperature on magnetic properties of FePt–MgO granular thin films on single-crystal MgO substrate

Abstract

(FePt) 100-x (MgO) x granular thin films were fabricated by using co-sputtering on single crystal MgO substrate at different deposition temperatures followed by a high-temperature annealing. The adding MgO was found to have the following effects: 1) high fraction of MgO phase (70 vol.%) degraded the L1 0 phase transformation; 2) FePt grains embedded in MgO matrix were well separated, leading to minimized exchange interaction between the FePt grains; 3) 55 vol.% fraction of MgO was optimal for the L1 0-FePt phase formation with highest coercivity, due to the formation of granular structure, which was also verified by comparing the structure and properties of FePt/MgO bilayer films. Deposition temperature has also effect on the magnetic properties of FePt-MgO films. Room temperature deposition did not result in the L1 0 phase even after annealing at 800°C. However, the magnetic properties of the films deposited at 200°C were better than those deposited at 300°C. The low coercivity resulted from elevated deposition temperature was attributed to the thermal expansion and competitively growth among FePt and MgO grains. The results revealed that adding appropriate amount of MgO (55 vol.%) can be achieved by finding a proper deposition temperature (200°C), well-defined granular L1 0-FePt films with fine grain distribution, high coercivity and small domain size.

Bias sputtering of granular L10-FePt films with hexagonal boron nitride grain boundaries

“…A list of GBMs, particularly carbon 3 – 6 , various oxides 7 – 14 , and boron nitride 15 – 17 have been given a great deal of attention over the past. Although amorphous carbon as the GBM enables well-separated grains, it fails to promote columnar growth 4 , 5 .…”

CoPt–Al2O3 Nanocomposite Films: Synthesis, Structure, and Magnetic Properties

“…Тонкие пленки FePd, FePt и CoPt, упорядоченные по типу L1 0 , обладают большой константой магнитной анизотропии K 1 (K 1 > 3 × 10 7 эрг/см 3 ) с осью легкого намагничивания, расположенной перпендикулярно поверхности пленки (так называемая перпендикулярная магнитная анизотропия). Нанокомпозитные пленки, которые содержат изолированные высококоэрцитивные L1 0 -кластеры, вложенные в немагнитную матрицу [18][19][20][21][22][23][24][25], могут быть использованы для магнитной записи информации с высокой плотностью.…”

“…В настоящее время имеется небольшое количество работ, посвященных получению и исследованию нанокомпозитов, содержащих наночастицы L1 0 -CoPt и L1 0 -FePt в оксидных матрицах [18,19,[22][23][24][25]. Для практических применений такие исследования необходимы, чтобы получать нанокомпозиты с заданными магнитными, структурными и транспортными свойствами.…”

Magnetic and Structure Properties of CoPt-In₂O₃ Nanocomposite Films

“…CoPt and FePt alloy films have attracted a great deal of attention because of their strong perpendicular magnetic anisotropy, which is important for many practical applications. To date, there have been a small number of studies on the synthesis and investigation of nanocomposites containing CoPt and FePt nanoparticles in oxide matrices [20][21][22][23][24][25][26]. These investigations are important for applications involving the synthesis of nanocomposites with the desired magnetic, structural, and transport properties.…”