Magnetic properties of epitaxial discontinuous Fe/MgO multilayers

We report magnetic, dynamic and transport properties of discontinuous metal-insulator multilayers Fe/MgO grown on amorphous Corning glass and single-crystalline MgO (001) substrates. The films of structure Substrate/MgO (3 nm)/[Fe (0.6 nm)/MgO (3.0 nm)] x 10 were prepared in ultra-high vacuum conditions using Pulsed Laser Deposition. It was shown that conditions of epitaxial growth are favorable for MgO substrates. As a result a substantial increase of tunneling magnetoresistance caused by spin-filtering effect was observed and reasonably theoretically explained. The value of TMR - 9.2% at room temperature in 18 kOe magnetic field is three times higher comparing to that for the samples grown on Corning glass substrates.

Determination of the percolation threshold in Fe/MgO magnetic granular multilayers

The evolution of the morphology, magnetic and transport properties of Fe(t nm)/MgO(3.0 nm) multilayers with respect to the nominal metallic layer thickness was investigated. A comparison with existing experimental data on discontinuous metal-insulator multilayers, ultrathin epitaxial Fe films on MgO substrates and granular cermet films is made. It is confirmed that the deposition conditions and the material composition play a crucial role in the percolation process. Nominal thicknesses of Fe layers at which an infinite metallic cluster is formed and the conditions for continuous Fe coverage were determined. Different methods of percolation threshold detection were analysed. We show that investigation of the temperature dependence of resistance in nanostructures could lead to an overestimation of the percolation threshold value, while magnetic measurements alone could lead to its underestimation.

Surgical synovectomy in haemophilic arthropathy of the knee

Twenty seven patients with haemophilia who had repeated haemarthroses affecting the knee joint, despite appropriate substitution therapy, were treated by surgical synovectomy. Open operations were carried out on 18 and 9 had an arthroscopic procedure. The average age at the time of synovectomy was 13 years for both the open and arthroscopic groups. The open group was followed up for an average of 15.2 years and the closed for 5.4 years. Operation took 70 minutes on average in the arthroscopic group and 50 minutes in the open. Patients who had an arthroscopy were in hospital for an average of 5 days and those with an open operation for 10. Synovectomy by both methods significantly reduced bleeding episodes. The results were assessed according to the classification recommended by the Orthopaedic Advisory Committee of the World Federation of Haemophilia. In the open group 2 patients had a good result, 10 were fair and 6 poor; in the arthroscopic group 3 had a good result, 5 were fair and 1 poor. Both operations appeared to slow, but did not halt, the radiographic deterioration of the joints.

Long term follow up of haemophilic arthropathy treated by Au-198 radiation synovectomy

Intra-articular injection of Au-198 (gold synoviorthesis) has been used in the treatment of repeated haemarthroses of the elbows, knees, or ankles in 64 haemophiliacs. These patients had continued to have joint haemorrhages despite appropriate, episodic, substitutive therapy over a period of more than six months. Follow-up for an average period of 14 years in one knee in 38 male haemophiliacs showed 8 good, 23 fair, and 7 poor results with regard to their joint scores. It is concluded that Au-198 is an effective agent for radiation synovectomy, particularly in the early stages of the disease with minimal radiographic changes. It appears to reduce the incidence of haemarthrosis and to slow the rate of evolution of radiographic changes.