A hard/soft SmCo5/Fe nanocomposite magnetic bilayer system is fabricated on x-ray transparent 100–200 nm thin Si3N4 films by magnetron sputtering. The microscopic magnetic domain pattern and its behaviours during magnetization reversal in the hard and the soft magnetic phases are studied separately by element specific magnetic soft x-ray microscopy at a spatial resolution of better than 25 nm. We observe that the domain patterns for the soft and hard phases show coherent behaviours in varying magnetic fields. We derive local M(H) curves from the images of Fe and SmCo5 separately and find the switches for hard and soft phases to be the same.

SmCo5/Fe65Co35 and SmCo5/Fe spring exchange magnets are fabricated by dc magnetron sputtering on MgO substrates and 100-nm-thick Si3N4 membranes, respectively. The base pressure of sputtering chamber is kept below 10−7 Torr, and Ar pressure is 3 to 8mTorr. The samples are characterized by an x-ray diffractometer, a superconducting quantum interference magnetometer, and high resolution magnetic soft x-ray microscopy. We obtain the complete exchange coupling and single phase behaviour of composite magnets. The (BH)max value achieved is 28.8 MGOe.

Trilayered Sm2Co7/Fe/Sm2Co7 spring exchange magnets are fabricated by dc magnetron sputtering on MgO substrates. Very thin layers (0.3-0.7 nm) of Cr and Ti are added at the interfaces of the two magnetic phases. The thickness of Sm2Co7 is kept at 20 nm and Fe at 6 nm while the thickness of Cr and Ti are varied as 0.3, 0.5, and 0.7 nm. The base pressure of sputtering chamber is kept below 10 −7 Torr and Ar pressure at 3-8 mTorr. The samples are characterized by x-ray diffraction (XRD) and SQUID magnetometer. We report improvement in exchange coupling of nonacomposite magnets by addition of thin layers of Cr at interfaces.

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