Abstract
We present a multifrequency electron spin resonance study in the range of 4–420 GHz of the quasi-one-dimensional, nondimerized, quarter-filled Mott insulators, . In the high-temperature orthorhombic phase above , the magnitude and the temperature dependence of the high-temperature spin susceptibility are described by a Heisenberg antiferromagnetic chain with and coupling constants for and Br, respectively. We estimate from the temperature dependence of the linewidth an exchange anisotropy, of . The frequency dependence of and the shift have an unusual quadratic dependence in all crystallographic orientations that we attribute to an antisymmetric exchange (Dzyaloshinskii-Moriya) interaction.
- Received 31 March 2010
DOI:https://doi.org/10.1103/PhysRevB.81.224438
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