Abstract
High-precision dc magnetization measurements have been made on in magnetic fields up to 14.7 T, slightly above the saturation field , in the temperature range from 0.08 to 15 K. The magnetization curve and differential susceptibility at the lowest temperature show excellent agreement with exact theoretical results for the spin- Heisenberg antiferromagnet in one dimension. A broad peak is observed in magnetization measured as a function of temperature, signaling a crossover to a low-temperature Tomonaga-Luttinger-liquid regime. With an increasing field, the peak moves gradually to lower temperatures, compressing the regime, and, at , the magnetization exhibits a strong upturn. This quantum critical behavior of the magnetization and that of the specific heat withstand quantitative tests against theory, demonstrating that the material is a practically perfect one-dimensional spin- Heisenberg antiferromagnet.
- Received 2 July 2014
DOI:https://doi.org/10.1103/PhysRevLett.114.037202
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