Optimization of Properties of a New Material for Electronic and Magnetic Applications
Abstract
Samples of MnAs/GaAs films have been prepared by molecular beam epitaxy with five different thicknesses, 200, 100, 50, 25 and 12.5 nm. The 200 nm film thickness was confirmed by optical microscopy and the 50 nm film was measured by on-edge high resolution scanning electron microscopy. The crystal structures of all films were determined by x-ray diffraction. In earlier work, two structures were found, which I call type A and type B. The 100 nm film is mainly type A while the others are entirely or largely type B. The magnetooptic Kerr effect has been used to measure the hysteresis curves of all samples. In some films a detailed study was made of the dependence of hysteresis behavior on direction of applied magnetic field. The films have large magnetizations and square hysteresis curves for the most part. Quite unexpectedly, the films have their magnetic easy and hard directions oriented the same way is in type A films, at ninety degrees to the type B directions found earlier. While the magnetizations are quite large, the coercive magnetic fields are larger than in the earlier films, i.e., these films are somewhat harder magnetically, which is advantageous for some applications. Additional films will be grown soon that are much thinner since we are interested in the thinnest films that are still ferromagnetic. We are now going to measure the effects of electric fields on the Kerr effect in the films. The earlier films were grown using a source of As2 while the present apparatus has a source of As4. The growth kinetics are different, but we now can readily grow type B structures. We might also now be able to grow type A, which would be preferred since its structure is simpler. In the next few weeks, we will very likely find out if increasing the electric field effects will work.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 14, 1997
- Accession Number
- ADA331339
Entities
People
- S. I. Kim