Structure of self-organized Fe clusters grown on Au(111) analyzed by Grazing Incidence X-Ray Diffraction

We report a detailed investigation of the first stages of the growth of self-organized Fe clusters on the reconstructed Au(111) surface by grazing incidence X-ray diffraction. Below one monolayer coverage, the Fe clusters are in "local epitaxy" whereas the subsequent layers adopt first a strained fcc lattice and then a partly relaxed bcc(110) phase in a Kurdjumov-Sachs epitaxial relationship. The structural evolution is discussed in relation with the magnetic properties of the Fe clusters.Comment: 7 pages, 6 figures, submitted to Physical Review B September 200

Cluster phase transition in insulating spin glass Ga<SUB>0.4</SUB>Fe<SUB>0.6</SUB>NiAlO<SUB>4</SUB>

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Cluster phase transition in insulating spin glass Ga<SUB>0.4</SUB>Fe<SUB>0.6</SUB>NiAlO<SUB>4</SUB>

M&#246;ssbauer effect, a.c. susceptibility and magnetisation studies (4.2&#x2266;T&#x2266;350 K, &#8722;20&#x2266;H&#x2266;20 kOe) show that in the mixed spined ferrite Ga<SUB>0.4</SUB>Fe<SUB>0.6</SUB>NiAlO<SUB>4</SUB>, spin freezing occurs via cluster formation. As in some other insulating spin glasses, the spin glass phase diagram transitions occur not for individual spins but for clusters whose effective spins' transverse and longitudinal components successively freeze. The presence of entropic spins and the centre shift of the field cooled hysteresis loop confirm the system's frustrated nature

Operation of prototype niobium gravitational radiation antenna with microwave parametric accelerometer

We report experimental results which confirm the feasibility of using a magnetically levitated noncontacting microwave accelerometer in conjunction with a high Q levitated niobium gravitational radiation antenna. Operation of a prototype antenna is described.Nous rendons compte de résultats expérimentaux qui confirment la possibilité d'utiliser un accéléromètre micro-onde associé à une antenne de radiation gravitationnelle en niobium à haut facteur de qualité, le tout soulevé par lévitation magnétique sans le moindre contact. On décrit le fonctionnement d'une antenne prototype