Li_0.9Mo₆O₁₇is a quasi-one dimensional (1D) superconducting metal whose single particle spectrum as measured by angle resolved photoemission spectroscopy (ARPES) has features generic to the T-dependent spectral function of the one-band Tomonaga-Luttinger model.  The ARPES spectrum of the dispersing excitation defining its quasi-1D Fermi surface shows a holon (charge mode) peak and a spinon edge dispersing with different velocities, and the k-integrated spectrum approaches the Fermi energy EF as a power law with anomalous exponent a.  A strong T-dependence of a [1] and the particulars of quantum critical scaling observed in the ARPES spectrum [2] can be traced to interacting gapped charge neutral critical modes that emerge naturally for Li_0.9Mo₆O₁₇ because two nearly degenerate bands cross EF. New band structure calculations and additional ARPES results conspire to imply the presence of a mechanism for suppression of perpendicular hopping that would otherwise destabilize the observed Luttinger liquid (LL) behavior.  Such a mechanism would constitute a scenario for a new quantum state of matter in which LL physics is maintained in dimension greater than one.

[1] Feng Wang et al., “New Luttinger-Liquid Physics from Photoemission on Li_0.9Mo₆O₁₇,” Phys. Rev. Lett. 96, 196403 (2006).
[2]  J. V. Alvarez et al, "Gap-protected Quantum Critical Scaling in ARPES of Li_0.9Mo₆O₁₇," submitted to Phys. Rev. Lett.

* Collaborators: J. V. Alvarez (Univ. Autonoma Madrid),  Feng Wang (Univ. of Michigan), S.-K. Mo (Stanford Univ.), G.-H. Gweon (Univ. of California, Santa Cruz), J. He (Clemson Univ.) , D. Mandrus (Univ. of Tennessee and Oak Ridge National Lab), R. Jin (ORNL), and H. Höchst (SRC, Univ. of Wisconsin).