4f spin density in the reentrant ferromagnet SmMn2Ge2

The spin contribution to the magnetic moment in SmMn2Ge2 has been measured by magnetic Compton scattering in both the low and high temperature ferromagnetic phases. At low temperature, the Sm site is shown to possess a large 4f spin moment of 3.4 +/- 0.1 Bohr magnetons, aligned antiparallel to the total magnetic moment. At high temperature, the data show conclusively that ordered magnetic moments are present on the samarium site.Comment: 5 pages, 2 figures, transferred from PRL to PRB (Rapid Comm.

Thermomagnetic history effects in SmMn2_2Ge2_2

The intermetallic compound SmMn$_2$Ge$_2$, displaying multiple magnetic phase transitions, is being investigated in detail for its magnetization behavior near the 145 K first order ferromagnetic to antiferromagnetic transition occuring on cooling, in particular for thermomagnetic history effects in the magnetization data. The most unusual finding is that the thermomagnetic irreversibility, [= M$^{FCW}$(T)-M$^{ZFC}$(T)] at 135 K is higher in intermediate magnetic field strengths. By studying the response of the sample (i.e., thermomagnetic irreversibility and thermal hysteresis) to different histories of application of magnetic field and temperature, we demonstrate how the supercooling and superheating of the metastable magnetic phases across the first order transition at 145 K contribute to overall thermomagnetic irreversibility.Comment: 15 pages, 5 figures, to appear in Physical Review

Magnetisation reversal in permanent magnet materials

SIGLEAvailable from British Library Document Supply Centre- DSC:DX173637 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Patterned magnetic media from self-assembly template methods

Using lyotropic liquid crystalline phases and self-assembly from colloidal suspensions of polystyrene latex spheres, well-ordered, nanostructured templates were prepared. The results of electrochemical deposition of magnetic metals and alloys in the voids of these templates are presented. This technique has enabled the creation of magnetic nanostructures with 3D-achitectures on length scales 4 nm-1 mum. Changes in coercive field, by more than an order of magnitude were found, dominated by the effects of domain wall pinning. Clear transverse magnetisation suggests Bloch type of the domain walls. The in-plane component of the magnetic field drives the magnetic hysteresis. The templated electrodeposition technique offers the potential of a low-cost preparation method for sub-micron patterned magnetic media

Determination of magnetostrictive stresses in magnetic rare-earth superlattices by a cantilever method

The magnetostrictive stress for a Ho6/Y6 superlattice has been determined at low temperatures by means of a capacitive cantilever technique. The magnetostrictive stress responsible for the basal plane distortion is found to be strongly enhanced with respect to bulk holmium. An explanation accounting for the unusual thermal dependence of that stress is offered