Electron spin resonance study of a CuIr₂S₄ single crystal

Abstract

A spinel sulphide CuIr₂S₄ single crystal, which exhibits an orbitally induced Peierls phase transition at ∼230 K, is investigated by electron spin resonance (ESR) spectroscopy. The phase transition is clearly manifested on the ESR spectra. It is suggested that the ESR signals are produced by a few non-dimerized Ir⁴⁺ ions. Moreover, an extra ESR spectrum appears at low temperature in addition to the paramagnetic ESR signals of Ir⁴⁺ ions, which is suggested to be caused by the Jahn–Teller effect of the non-dimerized Ir⁴⁺ ions. From the ESR results, it is found that the Jahn–Teller splitting energy ΔE _JT is much smaller than the spin-dimerization gap.

Keywords:

• spinel sulphide
• CuIr₂S₄
• orbital-induced
• Peierls phase transition

Acknowledgements

This work was supported by the National Natural Science Foundation of China through Grant Nos. 11004196 and 11004194, the Knowledge Innovation Program of the Chinese Academy of Sciences through Grant No. 106CS31121 (Hefei institutes of Physical Science, CAS), and the State Key Project of Fundamental Research of China through Grant No. 2010CB923403. Part of this work was performed at Brookhaven National Laboratory and supported by the US DOE under Contract No. DE-AC02- 98CH10886 (H. Lei and C. Petrovic).