In-plane magnetized YIG substrates self-biased by SmCo based sputtered film coatings

Abstract

Highly anisotropic SmCo based films with the TbCu7-type structure have been sputter deposited directly onto YIG substrates. The SmCo crystallites have the c axes approximately randomly splayed about the substrate plane such that the easy direction of magnetization of the SmCo film is in the film plane. The in-plane static energy product of the SmCo film layers was about 16 MG Oe. In-plane vibrating sample magnetometer hysteresis loops of the SmCo film and YIG substrate exhibit a composite form with the YIG field reversal shifted into the first quadrant by the looping field from the SmCo film layer. Approximately 4×4 mm2 pieces of YIG substrate have been measured to determine the YIG bias field and field required for reverse saturation of the YIG as a function of the SmCo based film layer thickness to YIG substrate thickness. It is observed that for SmCo to YIG thickness ratios greater than 0.22, the looping field from the SmCo film layer is sufficient to saturate the YIG magnetization in the reverse direction. SmCo film thicknesses in the range from 80 to 120 μm have been used in these studies. Special boundary layers have been used to promote thick film adhesion to the YIG substrates.

Preparation, Characterization, and Modeling of Ultrahigh Coercivity Sm–Co Thin Films

“…Numerous stacking faults (SF) can be observed in the basal plane of the grains, which is indicated with green arrows in Figure 4 a and b. Basal <a> dislocations can also be seen in Figure 4 a and b, marking the limit of the SF, the total extension of which typically reaches a maximum at half the grain diameter, corresponding to a quarter of the intercepted grain surface area. Projections of the Sm and Co atoms along the [11][12][13][14][15][16][17][18][19][20] direction are schematically shown in Figure 4 c …”

“…However, in certain applications where the hard magnetic fi lm is exposed to high demagnetizing fi elds and/or high operating temperatures, Sm-Co fi lms would be a better choice, due to the much higher values of magneto-crystalline anisotropy and thus high coercivity achievable in Sm-Co based materials. [11][12][13][14] We previously reported on the fabrication of high coercivity Sm-Co thin fi lms ( µ 0 H c ≤ 5 T at 300 K) by triode sputtering. [ 6 ] In this paper we demonstrate that the coercivity of Sm-Co based fi lms can be signifi cantly increased through a modifi cation of the target composition.…”

Magnetic properties and microstructure of Sm-Co/α-Fe nanocomposite thick film-magnets composed of multi-layers over 700 layers

“…This result is consistent with the previous report on a SmCo 5 film. 16,17 We calculated the energy E mag needed to magnetize the film from the demagnetized state (M ¼ 0, H ¼ H c ) to saturation, as shown schematically in the inset. E mag values were determined to be approximately 760 and 1080 kJ/m 3 for the in-plane and out-of-plane loops, respectively.…”

Advancement in NdFeB thick film magnets fabricated with YAG laser ablation system

“…Investigation on Sm-Co and Nd-Fe-B film magnets with the thickness of several 10 mm is accelerated in order to develop milli-size motors and micro-machines [1,2]. Although a dominant method for obtaining thick film magnets is sputtering, a disadvantage of this method includes the difficulty in obtaining deposition speed enough for a mass-production of miniaturized devices.…”