Abstract
True inorganic spin-Peierls materials are extremely rare, but was at one time considered to be an ideal candidate owing to its well separated chains of edge-sharing octahedra. At low temperatures, this material undergoes a phase transition from to symmetry, where dimers begin to form within the chains. However, it was quickly realized with magnetic susceptibility that simple spin fluctuations do not progress to the point of enabling such a transition. Since then, considerable experimental and theoretical endeavors have been undertaken to find the true ground state of this system and explain how it manifests. Here, we employ the use of x-ray diffraction, neutron spectroscopy, and magnetic susceptibility to directly and simultaneously measure the symmetry loss, spin singlet-triplet gap, and phonon modes. A gap of 53(3) meV was observed, fit to the magnetic susceptibility, and compared to previous theoretical models to unambiguously assign as having an orbital-assisted Peierls ground state.
- Received 26 June 2014
- Revised 9 September 2014
DOI:https://doi.org/10.1103/PhysRevB.90.140402
©2014 American Physical Society