Temperature-dependent luttinger surfaces

The Luttinger surface of an organic metal (TTF-TCNQ), possessing charge order and spin-charge separated band dispersions, is investigated using temperature-dependent angle-resolved photoemission spectroscopy. The Luttinger surface topology, obtained from momentum distribution curves, changes from quasi-2D (dimensional) to quasi-1D with temperature. The high temperature quasi-2D surface exhibits 4k(F) charge-density-wave (CDW) superstructure in the TCNQ derived holon band, in the absence of 2k(F) order. Decreasing temperature results in quasi-1D nested 2k(F) CDW order in the TCNQ spinon band and in the TTF surface. The results establish the link in momentum space between charge order and spin-charge separation in a Luttinger liquid.