Electrical transport properties of thin rare earth metal wires and films
Thin wires of several heavy rare earth metals (Gd, Tb, Dy, Ho and Er) have been fabricated using a step-edge lithographic technique with cross section area from 0.87 x 10{sup {minus}11} cm{sup 2} to 58 x 10{sup {minus}11} cm{sup 2}. The electrical resistances of thin wires were measured by a four probe method in the temperature range from 1.5 K to 300 K. With decreasing temperature the resistance of the Gd, Tb, Dy and Ho wires has a consistent sharp drop at {approx}25 K, {approx}20 K, {approx}6K and {approx}5 K respectively. The Er wires do not consistently show this sharp drop. The sharp drop of resistance was shown by three methods to be consistent with a ferromagnetic transition: the temperature derivative of resistance, the character of temperature dependence and the magnetoresistance measurement. The driving force of the suppressed ferromagnetic transition was originally interpreted as an effect of electron localization. Then the effect of substrates was checked by fabricating thin wires on sapphire (single crystal) and cover glass (amorphous solid). The effect from rare earth compounds was examined by matching the suppressed transition temperature to that of the single two element rare earth compounds. Both failed to interpret the causation. The structure of thin films was examined by TEM and X-ray diffraction. These showed that the thin films are polycrystalline with mixed f.c.c. and h.c.p. structure and the (002) plane of h.c.p. structure predominates the lattice orientation respectively. Thin films without Ar ion milling showed the suppressed ferromagnetic transition to be thickness dependent, while this transition occurred in all milled films with different thicknesses. This phenomenon is able to be interpreted by the magnetoelastic effect, which can also interpret the unchanged antiferromagnetic transition for Tb, Dy and Ho wires. This magnetoelastic effect cannot interpret the length effect on Tb wires.
- Research Organization:
- Southern Illinois Univ., Carbondale, IL (United States)
- OSTI ID:
- 114787
- Country of Publication:
- United States
- Language:
- English
Similar Records
/sup 121/Sb Moessbauer investigation of the rare earth antimonides