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Raman micro-spectroscopy is well suited for studying a variety of properties and has been applied to wide- ranging areas. Combined with tuneable temperature, Raman spectra can offer even more insights into the properties of materials. However, previous designs of variable temperature Raman microscopes have made it extremely challenging to measure samples with low signal levels due to thermal and positional instability as well as low collection efficiencies. Thus, contemporary Raman microscope has found limited applicability to probing the subtle physics involved in phase transitions and hysteresis. This paper describes a new design of a closed-cycle, Raman microscope with full polarization rotation. High collection efficiency, thermal and mechanical stability are ensured by both deliberate optical, cryogenic, and mechanical design. Measurements on two samples, Bi2Se3 and V2O3, which are known as challenging due to low thermal conductivities, low signal levels and/or hysteretic effects, are measured with previously undemonstrated temperature resolution., 11 pages, 13 figures

Cr2Ge2Te6 is proposed as an insulating ferromagnetic substrate for the growth of tetradymite-type topological insulators, based on a refined characterization of its transport, magnetic, optical, and calculated electronic properties. It is found to be a soft ferromagnet with no visible magnetic domains over relatively large length scales and to be highly insulating with an indirect band gap and low carrier concentration. Further we present the fabrication of Bi2Te3-Cr2Ge2Te6 heterostructure samples by chemical vapor deposition and show that crystals of the two phases are oriented such that the hexagonal Te planes are aligned at their interfaces. V C 2013 AIP Publishing LLC.