EVOLUTION OF FERROMAGNETISM IN SELF-INTERCALATED CHROMIUM TELLURIDES

Abstract

In this thesis chromium-tellurides were synthesized via solid state reaction and single crystals were grown via chemical vapor transport reactions. Both monoclinic and hexagonal Cr7Te8 phases were synthesized and magnetic susceptibility measurements and field sweeps were preformed. Arrott plots were generated to determine the exact Curie temperature of the monoclinic and hexagonal phases of 328K and 342K respectively. The disordered phase sample shows a unique meta-magnetic transition around 70K. Neutron diffraction was taken on the meta-stable hexagonal phase and magnetic structures were solved showing a simple ferromagnetic arrangement at room temperature followed by a change in easy axis at 150K, and finally a spin-recant to the c-axis at 5K. The addition of an anti-ferromagnetic component and a magnetic propagation vector of k= (1/2, 1/2, 0) was also observed at 5K. Single crystals were then grown via chemical vapor transport and macro-magnetic properties were measured utilizing a SQUID magnetometer. Several samples showed the same meta-magnetic transition around 70~K with exotic susceptibility data between in and out of plane measurements. Finally, this works next steps should include single crystal neutron diffraction of the monoclinic, trigonal, and hexagonal phase single crystal samples to elucidate the exotic magnetic structures hinted at by the susceptibility data.