Spin and orbital frustration in FeSc2S4 probed by Sc45 NMR
Abstract
We report on Sc45 NMR experiments in the geometrically frustrated spinels FeSc2S4 and MnSc2S4 . The temperature dependences of line shift K(T) , linewidth Δ(T) , spin-spin relaxation rate 1/T2(T) , and spin-lattice relaxation rate 1/T1(T) are deduced. The manganese compound reveals the behavior of a long-range ordered antiferromagnet, but with the onset of critical spin fluctuations at unusually high temperatures of 40 TN . K(T) of FeSc2S4 exhibits a cusplike maximum, a hallmark of spin frustration. Orbital fluctuations strongly enhance 1/T1(T) at elevated temperatures. Toward lowest temperatures these fluctuations slow down resulting in an increase of 1/T2(T) . The exponential decrease of 1/T1(T) results from the opening of a spin gap Δ=0.2meV , a characteristic feature of a spin liquid.
- Publication:
-
Physical Review B
- Pub Date:
- April 2006
- DOI:
- 10.1103/PhysRevB.73.132409
- Bibcode:
- 2006PhRvB..73m2409B
- Keywords:
-
- 75.50.Bb;
- 71.70.Ej;
- 75.40.Gb;
- 76.60.-k;
- Fe and its alloys;
- Spin-orbit coupling Zeeman and Stark splitting Jahn-Teller effect;
- Dynamic properties;
- Nuclear magnetic resonance and relaxation