Henderson, A. | Search NASA

DOE OSTI2018

Weak ferromagnetism and glassy state in κ - ( BEDT - TTF ) 2 Hg ( SCN ) 2 Br

SInce the first observation of weak ferromagnetism in the charge-transfer salt kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Cl [U. Welp et al., Phys. Rev. Lett. 69, 840 (1992)], no further evidence of a ferromagnetic state in this class of organic materials has been reported. Here, static and dynamic spin susceptibility measurements on kappa-(BEDT-TTF)(2)Hg(SCN)(2)Br exhibit weak ferromagnetism below 20 K on the geometrically frustrated background. Our experimental results suggest that frustrated spins in the molecular dimers suppress long-range antiferromagnetic order, forming a spin-glass-type ground state of the triangular lattice in the insulating phase which locally contains ferromagnetic polarons. Moreover, specific-heat data reveal an excess peak located around 5 K, indicating the glassy nature of the electrons as well.

Hemmida, M.↗

NASA NTRS1984

Project Explorer

PROJECT EXPLORER is a program that will fly student-developed experiments onboard the Space Shuttle in NASA's Get-Away Special (GAS) containers. The program is co-sponsored by the Alabama Space and Rocket Center, the Alabama-Mississippi Section of the American Institute of Aeronautics and Astronautics, Alabama A&M University and requires extensive support by the University of Alabama in Huntsville. A unique feature of this project will demonstrate transmissions to ground stations on amateur radio frequencies in English language. Experiments Nos. 1, 2, and 3 use the microgravity of space flight to study the solidification of lead-antimony and aluminum-copper alloys, the growth of potassium-tetracyanoplatinate hydrate crystals in an aqueous solution, and the germination of radish seeds. Flight results will be compared with Earth-based data. Experiment No. 4 features radio transmission and will also provide timing for the start of all other experiments. A microprocessor will obtain real-time data from all experiments as well as temperature and pressure measurements taken inside the canister. These data will be transmitted on previously announced amateur radio frequencies after they have been converted into the English language by a digitalker for general reception.

Dannenberg, K. K.↗