Tuning magnetic properties of BiFeO3 thin films by controlling Mn doping concentration

Enhanced Magnetic Properties of Co-Doped BiFeO3 Thin Films via Structural Progression

“…According to group theory, BFO displays 13 optical-phonon active modes (4A 1 + 9E) with space group R3c [ 22 , 23 ]. The 4 modes at 149.6, 170.0, 217.6 and 436.1 cm −1 can be designated as A 1 –symmetry longitudinal optical modes [A 1 -1, A 1 -2, A 1 -3, A 1 -4 (LO)], and 8 modes at 77.0, 265.6, 318.7, 345.4, 369.2, 482.3, 515.6 and 617.8 cm −1 are associated with transverse optical E(TO) (E-1, E-2, E-3, E-5, E-6, E-7, E-8, E-9 (TO)) phonons [ 24 , 25 ]. In this work, the E-8 mode of BFO thin film overlaps with the Raman vibration mode of silicon substrate.…”

“…In this work, the E-8 mode of BFO thin film overlaps with the Raman vibration mode of silicon substrate. The results of first-principles calculation have revealed that the Bi-O vibrations only participate in the low-frequency region of the A 1 modes and the Fe–O vibrations mainly participate in the high-frequency region of the E modes [ 24 , 25 , 26 , 27 ]. Compared with that of pure BFO, the peak positions of Raman spectra of BFCxO are slightly red-shifted, and the intensity decreases as Co doping concentration increases.…”

“…When begins to deflect from the ideality of 180°, the anti-symmetric exchange energy term will increase. In summary, several possible factors may account for the enhancement of magnetic properties for Co-doped BFC x O thin films: (i) an increased Fe–O–Fe spin angle results in the net macroscopic magnetization [ 25 , 36 , 37 , 38 ]; (ii) the suppression of the spin cycloid spiral modulation structures will release magnetism [ 25 , 26 , 27 , 28 , 29 , 39 ]; (iii) enhanced ferromagnetic properties are attributed to the super-exchange interaction between both d 6 and d 5 electronic configurations of Co 3+ and Fe 3+ [ 25 , 26 , 27 , 28 , 29 , 39 ]; (iv) Fe 3+ ions are randomly replaced by Co 3+ ions, resulting in the non-compensation of the spins on the surface of grains and making grain size closer to or less than the cycloidal modulation wavelength of ~62 nm [ 25 , 26 , 27 , 28 , 29 , 39 , 40 , 41 , 42 ]. Accordingly, it is an important way to improve the magnetic behavior of BFO thin films, which is beneficial for the application in subminiature devices and information storage.…”

“…It is also caused by the smaller radius of the Co ions, and correspondingly, the lattice collapses and oxygen vacancies are formed [26][27][28][29]. To further investigate the structural changes of all thin films with doping concentrations, we carried out Raman spectra measurements on BFO and BFCxO thin films, as shown in [24,25]. In this work, the E-8 mode of BFO thin film overlaps with the Raman vibration mode of silicon substrate.…”

Evidence of substrate roughness surface induced magnetic anisotropy in Ni80Fe20 flexible thin films

“…To achieve desired functionalities, magnetic thin films must be fabricated with precise and controllable properties such as coercive field (H c ), saturation magnetisation (M s ) and the magnetization reversal profile of the hysteresis loop. Various commonly used control methods of these parameters are doping [21], the use of suitable substrates [22] and seed layers [23] and thermal annealing [24] during and post deposition. A highly influential control mechanism of magnetism in thin films is also the actual process of thin film coating, together with the choice of deposition parameters.…”