Rapid thermal annealing of CeDyGaIG films for magneto-optical disk storage

Abstract

CeDyGaIG is a potential candidate for magneto-optical storage media because of its very good properties on a wide scale of wavelength. The high crystallization temperature of oxide media poses difficulties with the classical materials used for magneto-optical disks. In order to solve this problem we have used a rapid-thermal-annealing (RTA) process to crystallize amorphous CeDyGaIG thin films deposited by facing-target sputtering method on glass substrates. We have succeeded in crystallizing CeDy2Ga0.4Fe4.6O12 amorphous sputtered thin films on these substrates by RTA. The films made by this method have the same optical properties as those crystallized in situ. With the RTA method, we can adjust, by an appropriate process, the coercive field between 250 and 4000 Oe. The influence of the sputtering parameters on the grain size and boundaries was analyzed by transmission electron microscopy. On RTA crystallized films, bit information was written. In conclusion, we discuss the evolution of the magnetic properties versus the temperature and conditions of RTA annealing.

Investigation of Cerium-Substituted Europium Iron Garnets Deposited by Biased Target Ion Beam Deposition

“…The chemical composition of the individual metal oxide films were determined by electron microprobe analysis (EPMA) (JOEL 8530) while the composition of the garnet film was determined by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). A two stage post deposition heat treatment [12] was performed using a rapid thermal annealer (RTA ASONE-100). The first stage consisted of annealing at 750ºC under vacuum for 3 minutes to suppress the Ce 4+ oxidation state.…”

“…Cerium substituted RIG (Ce:RIG) thin films have been fabricated using a variety of techniques, including sputtering [10][11][12], pulsed laser deposition [13], plasma enhanced metal organic chemical vapor deposition [4], metal organic chemical liquid deposition [4] and sol gel [14]. Our approach uses a relatively new technique known as biased target ion beam deposition (BTIBD) [15].…”

“…In order to maintain the garnet structure, cerium substitution into the YIG should predominantly be in the form of Ce 3+ ions. However, under most conditions used for the preparation of garnet materials the cerium is likely to be in the Ce 4+ state and additional mechanisms need to be used to ensure the preferred Ce 3+ oxidation state in the cerium substituted iron garnet films, using techniques like hydrolysis of alkoxides [14] and annealing techniques [12,18] .…”

Rapid thermal processing of magnetic materials

“…However, the films deposited on these substrates exhibited low CNR's due to unfavourably increased media noise. The low CNR may be due to the inability to write circular domains in these substrate materials [84] or due to its origin from grain-boundary light diffusion [85].…”

“…Ce-substituted CeDyGaIG film has large magnetooptical properties in the range of near infrared. Bechevet et al [85] investigated as-deposited amorphous CeDyGaIG (CeDy 2 Ga 0.4 Fe 4.6 O 12 ) films crystallized using an RTP furnace with 1 kW lamp power with variable pulse width (0.5-2.5 s). The coercivity of films processed under vacuum was increased after prolonged RTP under ambient atmosphere.…”