New High-Field Phase in the Spin-Peierls System, Tetrathiafulvalene-CuS4C4(CF3)4

Abstract

New magnetization data on the spin-Peierls system tetrathiafulvalene-Cu${\mathrm{S}}_4$ ${\mathrm{C}}_4$ ${\left(\mathrm{C}{\mathrm{F}}_3\right)}_4$ for $h<~155$ kOe and $T>~1.5$ K provide evidence for a new phase above $h\sim 115$ kOe. Considerable hysteresis in the field-induced transitions is observed for $T<~5.5$ K. These results are discussed in the light of current theoretical ideas.