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© 2008 Elsevier B.V. This work was partially supported by the following Projects: ESP2006-09935, Spanish ‘‘Ministerio de Educación y Ciencia’’; S-0505/MAT-0279, Spanish ‘‘Comunidad de Madrid’’; FP7-SEC- 2007-01, European Commission, and Contract number 14240/00/ NL/SH, European Space Agency. One of the authors VC is thankful to the Ministry of Education and Science, Spain for the financial support. The author NV is grateful to Department of Science and Technology, Govt. of India for providing the BOYSCAST fellowship. The author JRF is thankful to the Universidad Autónoma of Madrid for financial support., The II-VI compound semiconductor crystal cadmium zinc telluride (CZT) is very important in the field of room-temperature radiation detectors and medical imaging applications. In the present study, bulk CZT single crystal has been grown by (i) oscillatory Bridgman technique, (ii) from vapour phase using pyrolytic boron nitride ampoule in the Bridgman geometry, and (iii) by using a Pt tube used for the ampoule support as a cold finger. Several improvements were found in the thermal environments such as the effects of superheating and reduced growth velocity, as well as improvements in the grain size and zinc composition along the ingot. The compositional homogeneity and its current-voltage characteristic behaviour have been analysed using energy dispersive X-ray analysis and I-V method, respectively., España. Ministerio de Educación y Ciencia, Comunidad de Madrid, European Commission, European Space Agency, Department of Science and Technology, Govt. of India, Universidad Autónoma de Madrid, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

© 2009 American Institute of Physics. This work was partially supported by the following Projects: Grant Nos. MEC-ESP2006-09935, CM-S-0505/ MAT-079, and FP7-SEC-2007-01 “European Commision,” and Contract No. 14240/00/NL7SH “European Space Agency.” One of the authors, V.C., thanks MEC, Spain for financial support. N.V. is grateful to Department of Science and Technology, Government of India for providing the BOYSCAST fellowship. The author J.R.F. is thankful to the Universidad Autónoma of Madrid for the financial support., Cadmium zinc telluride, CdZnTe, bulk single crystals doped with 10^19 at./cm^3 of indium in the initial melt were grown by vertical Bridgman technique. The samples were investigated by energy dispersive spectroscopy, cathodoluminiscence (CL), and current-voltage behavior at room temperature. The results shows that Cd and Te vacancy concentration depend on the indium and zinc concentrations. CL measurements indicate a relationship between radiative centers associated to Cd and Te vacancies and resistivity values., European Commision, European Space Agency, Department of Science and Technology, Government of India, Universidad Autónoma de Madrid, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Scientific interest in iron-oxides and in particular magnetite has been renewed due to the broad scope of their fascinating properties, which are finding applications in electronics and biomedicine. Specifically, iron oxide nanoparticles (IONPs) are gathering attraction in biomedicine. Their cores are usually constituted by a mixture of maghemite and magnetite phases. In view of this, to fine-tune the properties of an ensemble of IONPs towards their applications, it is essential to enhance mass fabrication processes towards the production of monodisperse IONPs with controlled size, shape, and stoichiometry. We exploit the vacancy sensitivity of the Verwey transition to detect the presence of magnetite. Here we provide direct evidence for the Verwey transition in an ensemble of IONPs through neutron diffraction. This transition is observed as a variation in the Fe magnetic moment at octahedral sites and, in turn, gives rise to a change of the net magnetic moment. Finally, we show this variation as the microscopic ingredient driving the characteristic kink that hallmarks the Verwey transition in thermal variation of magnetization.

A series of GdCu [Math Processing Error] nanoparticles with controlled sizes ranging from 7 nm to 40 nm has been produced via high-energy inert-gas ball milling. Rietveld refinements on the X-ray diffraction measurements ensure that the bulk crystalline [Math Processing Error] structure is retained within the nanoparticles, thanks to the employed low milling times ranging from t = 0.5 to t = 5 h. The analysis of the magnetic measurements shows a crossover from Superantiferromagnetism (SAF) to a Super Spin Glass state as the size decreases at NP size of [Math Processing Error] 18 nm. The microstrain contribution, which is always kept below 1%, together with the increasing surface-to-core ratio of the magnetic moments, trigger the magnetic disorder. Additionally, an extra contribution to the magnetic disorder is revealed within the SAF state, as the oscillating RKKY indirect exchange achieves to couple with the aforementioned contribution that emerges from the size reduction. The combination of both sources of disorder leads to a maximised frustration for [Math Processing Error] 25 nm sized NPs